D&D 5E What DM flaw has caused you to actually leave a game?

I've read many threads on what makes a good DM, DM pitfalls, and, most recently, the "worst" thing a DM can do. These threads often have many posts with hyperbolic language about how the poster would walk out on any DM who does X. In some cases, such as abusive behavior, I can understand leaving the group and even walking out mid-session. But in many cases, the walk-out worthy behavior is something like "rail-roading", calling for perception checks before asking what the PCs are doing, or not using a DM screen. Really?!

So, a more interesting question to me is what real-life behavior has led you or a player you know to *ACTUTALLY* leave a game. In particular, I'm interested in game-specific behavior. Obviously, abuse, poor hygiene, or lack of social skills might drive you away from a game, just as they would in other social situations. But what game style, rulings, cheating, game behavior, use of or lack of game aids, and other game-related behavior on the part of a DM has actually led to you leaving a game.

I'll start. Difficulty communicating about schedules. Showing up to play only to find out that the game has been canceled with no warning--if that happens to many times, I stop going. This has always been a DM running games at FLGS. I guess they just assume that you'll be hanging out at the store and not both to consider that you arrange your schedule and rush from work, fighting rush-hour traffic to make the game on time.

I know that scheduling etiquette is not game specific, but I can't think of any game style, homebrew rule, or ruling that has caused me to leave a game. I pretty much go with the flow and can find enjoyment with all kinds of DM styles.

Nothing so far.
Normally if there's a problem or a player is frustrated, we talk about it. I'm playing mostly with friends (and their friends), so this option is always there. I guess it can be trickier if you play at stores and with people who aren't necessarily your friends or even complete strangers.

I think a session zero is a good place to talk about expectations and requests, not only regarding the DM but also the players. As a DM I'd reserve a couple of minutes for complaints and ideas before or after a session, so I have feedback I can act upon, if I myself don't notice a bad mood or frustration.
This is of course the standard "communication solves it all" argument, but in my experience it works pretty well.

I'll drop game quickly if for me the GM style doesn't suit the game being run. Eg for 5e D&D and similar (3e, 4e), don't nerf core PC class abilities in the interest of simulation. If you don't understand the rules, either look them up, or accept advice from a reliable player. Viking Hat DMing is fine in 1e or 2e, not so much in 3e-5e.

Combination of factors drove me away once from a table but the most egregious for me was a lack luster campaign.

Traveller game forever and z day. GM blocked any attempts to perform routine tasks like buying gear at spaceport - literally down to failing to use phone book. After I just had my character sit and wait, patron shows up with mission and gear as the carrot. NOTE was not situation of sellers refused to sell to us due to fear of Patton, but just characters could not succeed at getting to find vendor.

Did not return after vendor offer.

Hero system - difference in campaign preference - session starts with team outside mall held hostage. The other players extolled how they cut out the "in your secret I'd, alarm goes off how do you get yo mall" role playing stuff to allow more time for fight. Amicable departure.

Dnd like 3 something. Mission into goblin lair led to only ways being narrower and narrower tunnels where we did ourselves damage moving thru them. Frustrating hour. Some goblin sniping. Then goblin appears halfway inside our line and runs past the rest of us sardines with no problem running by us.

Did not return.

Game billed as online homebrew dnd 5e. Turns out yo ne some mom port of his favorite mom with nothing remotely 5e. Also, rules for using abilities seems to change weekly. Also, advancement options at leveling must be done over phone during game.

Did not return after the 2nd or so when one PC kept trying to kill another.

Game where GM was trying to use game to out a player.

Everyone who left my games so far just... disappeared. Not coming online anymore, not answering mails, etc.
I don't think something I did as DM caused anyone to do that. I'm very clear already when recruiting players what type of DM I am and the players applying are those that love exactly my type of play. So I usually just get positive feedback.

The things I don't like about other DMs actually caused me to never join a game as player ever. So I didn't really have the chance to up and leave yet. AL would be perfect for me but it's not available in my country. And I just can't find a non-AL DM that is rule-strict enough for me to accept him as suitable. It already starts with the DM not allowing Goodberry to be combined with Life Cleric bonus. Or a DM that thinks that hiding ends if you are vaguely seen. Just can't join such a DM.

I could imagine how this would go:

Me: "I'm a life cleric, so each goodberry recovers 4 HP."
DM: "Nope, that's not how it works."
Me: "Oh of course it does. Jeremy Crawford replied to this and confirmed it on Sage Advice, look it up if you don't believe me."
DM: "Then I just make a houserule that it doesn't work like that on my table."
Me: "You can't just change the rules, you didn't create this game, Wizards of the Coasts did."
DM: "The DM is allowed to change the rules."
Me: "No he's not. The DM is just another player, except he's playing a lot more characters and has the job to tell the other players what they perceive."
DM: "That's not how I see it."
Me: "Fine, that's it, I'm out."

Yeah no, I don't want to run into such a situation ever, so I guess I'll have to live with being DM myself forever, despite really wanting to be player too.

Extreme Railroading. There is no point in having players at a table if you don't allow them to influence the story. There is nothing wrong with it, but you're an author, not a DM. Just write a book instead.

[edit] Technically, I did not walk away from that table. We addressed the DM about this problem, and the DM walked away from the table.

I am a fiirm believer that no gaming is better than bad gaming. I've left a lot of games over the decades.

I left games over DM restrictions that made no sense. For example, one game of 1e, I created a Magic-User as did a second player. We each got some interesting spells and wanted to trade with each other. The DM said we couldn't; apparently he wanted our spell lists to remain unique so our PCs were distinct. So I left.

I left games when it became obvious the DM was interested in playing my character. "Your character wouldn't do that." is a sure sign I'm leaving.

I left games when the DM was obviously not into running. Cancelling with limited notice, getting started very late, obviously unprepped and unprepared to run when games actually went ahead.

I left games over DM behaviour towards the players. I've seen both blatant favortism and antagonism and abandoned games for both.

I left games when player-to-player animosity got too much whether I was personally involved or not.

I left games over bait-and-switch campaign alterations. For example, one game I started was sold as a Traveler-esque game using Hero system rules. About 5 sessions in, the universe was destroyed and the PCs ended up in Chivalry and Sorcery. Another was an Aftermath campaign sold as the PCs were sailing up the Mississippi delta. About 10ish sessions in we discovered the PCs were in a dome on a Starlost style generation ship which invalidated a couple of backstories (the dome was 20ish miles across and one PC was a fighter pilot from California).

I left games when the house rules and rulings in play changed wildly from session to session without obvious reason or notification.

I left games over undisclosed but material house rules that substantialy impacted my character and its future development. Upon disclosure I ask myself if I would have joined the campaign if it had been disclosed at the start and if the answer is no, I leave.

I left a game when the colour of the game started to veer wildly away from PG-13. I don't want to paticipate in group phone-sex or torture porn, thanks.

The only game I've left recently was due to a combination of railroading and favouritism. We were playing a zombie apocalypse game where we initially were heading towards an army base - but after things hotted up in that direction we decided we were better off changing course, and finding a nice inaccessible island to hole up on. So the GM had a bunch of army helicopters catch up with us, despite the fact that they had no clue where we were, on the flimsy grounds that one of the PCs had useful medical experience and could help them with research.

So we got taken to the base anyway, and the medic PC was immediately put to work on interesting classified research, while everyone else was locked out of anywhere important and put to work doing menial camp-building labour that was just as boring out-of-character as it was for our PCs. And that was the rest of the session - another three hours mostly focused on one player, occasionally cutting back to us to check how we were getting on at putting up tents and digging latrines.

A few things will cause me to leave a campaign, but I think it basically comes down to style, especially if it's not broadcast ahead of time. For example, one campaign was a "joke" campaign. By someone who thought he was hilarious when he really wasn't. For example we go into a nearby town to get supplies and ask a guy his name. His name is Bob. Then his wife joins him her name is Bob as well. Yep. We had just discovered Bobtown where everyone was called Bob. This guy cracked himself up.

In another case, it was obvious everyone else was running an evil PC. Which is fine - if I ever wanted to play in that kind of campaign. I don't and wasn't interested. Could have saved some time if they had just let us know up front.

The rules are the rules kind of guy. Especially bad house rules. Like the guy that loved his critical hit/miss charts. Fun thing like the enemy rolls a 20, you lose a limb. Possibly your head based on a 6 sided dice that had different body parts on it. Apparently every enemy had light sabers. Roll a 1? If you were lucky you just dropped your weapon or accidentally threw it across the room. If not, it shattered even if magical.

You will have my kind of fun guy. Had a DM who thought rolling for stats was the only way to go. We asked if we could use point buy he said no. Then my wife rolled poorly (a single 14, a couple of 10's, everything else much lower) while someone else at the table rolled multiple 18s, nothing below a 14. She asked if she could reroll or use point buy. Nope. Had to play that character because it was "fun". It's fine if everyone likes this style of play.