I haven't jumped in on PF2 threads in some time since the game failed to win over the group and we've reverted back to 3e/PF1 or 5e in the cases where we wish to scratch rules-heavy itches vs "just sit down and game" itches.
PF2 is definitely regarded by our group as "rules play" - great if you want to sit alone and just look at rules and think about rules and think about rules interactions or roleplay as a game designer. I could imagine the trajectory being in PF3 something along the lines of "Now 4 actions per round! More fun!" And "now 6 degrees of success!". And "+2 to level on trained checked vs +1 to level on untrained". This is a bit tongue in cheek but hopefully illustrates the slippery slope.
Maybe your gaming group all command rules mastery but having to go back a round because "oh crap I missed that was a critical success or failure" is painful. Or the "wait, you have 1 more action this round". Gameplay we spend a lot more time talking about rules than using our imaginations about what is going on in the room we're in and trying to knock over tables or cut down chandeliers
It's been a while but I can cite one example where there was an NPC interaction and the group was trying to fib to the NPC, "oh yeah we're in favor of Duke so-and-so taking charge too". A totally valid thing we'd all do at a neighborhood BBQ to try to bond with a neighbor, "oh yeah I'm totally voting for the same president as you are". But the rules suggest that this won't improve that NPCs attitude towards you for successfully delivering that fib. Instead there's a feat, "Charming Liar" which lets you accomplish what Diplomacy would in terms of attitude adjustment, but only a critical success. Imagine having to explain this to my grade school son and shut down what for him is a brilliant epiphany on social interaction by explaining he should have run across this feat and planned it in advance?
The TLDR is that feat heavy systems, especially if they want to get you to purchase a dozen books over the years, will inevitably end up gating good ideas and if there's a person at the table with disparate rules mastery, they'll potentially call out the rule(s) that were applicable. It's fine with a home group of friends because your DM can handwave it as long as everyone shares roughly the same philosophies of rules-getting-in-the-way. I think in our limited play of PF2, the gentleman's agreements ended up just imagining every PC had over a dozen or so feats we encountered would've gated play - "just imagine anyone creatively problem-solving can use this rule or a rough approximation of it". Of course then that leads to character building questions, "can I just assume we'll all have this feat in play so I don't have to take it?". If I were to be in charge of PF3, I'd take maybe one third of the feats and put them in a GM Advice Guide (which I know would be a bummer for revenue vs sprinkling them out over a dozen supplements players building PCs could buy to get power) as "suggestions to adjudicate creative player ideas". Or, just trickle the feats-as-advice out via free blog posts to encourage DM creativity.
There's plenty of DM's who will take on PF2's rules mastery challenge and try to commit it all to memory but if you are new to the hobby it's daunting with just a handful of supplements, especially as PF2 has tended to attract the players who crave rulesplay away from the table and will bring that rules mastery into a session and battle it with the DM over small nits.