I would love to have you outline your thoughts here.
I think that a lot of this comes down to positions which are largely intuitive for a lot of people - and so which makes it hard to properly describe - with regard to who arbitrates what areas of a shared fantasy. The obvious point of demarcation here is the interaction between the PC and the game world, where the player is in charge of the former and the DM the latter. As with so many things, where they interact brings up questions of who has "jurisdiction" (for lack of a better word).
The traditional answer, to my mind, has been that the DM is understood to be the authority in the event of a conflict, and that by sitting down to play the players tacitly agree to that. Of course, this comes with an equally tacit understanding of the social contract in that the DM is going to act in a manner that's deserving of the players' trust, not doing anything that they would expect to be upsetting (though mistakes and accidents can still happen, which is why Session 0 has been a thing since long before it was ever called "Session 0").
Having said that, if there's no disagreement that the DM isn't acting in bad faith, then I personally think that there's room for the DM to narrate the PCs reactions to events, typically in a cosmetic manner that fleshes out a die roll (i.e. describing how a proposed action plays out). I also think that it's understood that they'll need to arbitrate disputes, and that them finding that their own judgment carries more weight is not in-and-of-itself evidence of them being on a power-trip. Even if a player isn't being disruptive, and has made an understandable assumption, it's okay to tell them "no."
In a less general sense, I'm also personally leery of after-the-fact (even if it's immediately after) instances of a player introducing something which changes their interaction with a particular scenario. Even if it avoids issues of stepping into the DM's milieu (Gygax buzzword!) by restricting it to what the PC has on them, that simply opens a door that I'd rather remain firmly shut. I don't want there to be debates about a face mask providing advantage against inhaled gasses, or steel boots providing immunity to caltrops. While I won't say that's inherently an issue of a player acting in bad faith, I find that it changes the nature of the game (albeit only in a minor fashion) in a way that I don't care for.
Overall, I'd say that in the event of a conflict where both sides are being relatively reasonable, and arguing in good faith, the DM should get to make the call, everyone accepts it (regardless of what it is) and moves on. Ideally while figuring out a way to make sure that particular point of friction doesn't come up again at a later date.