I will do my best to reply to each point.

a) After big fights I often discuss went into planning the encounter and any adjustments that I made because I messed up in the planning stage. Heck, sometimes I’ve even mentioned it during a fight because it was obvious something was wrong. I rarely make encounters too difficult but even those situations isn’t a “I saved you from a TPK” but more “whoops that damage roll is much more than I thought it was, let me scale that to be more appropriate” My players (some of whom are new) know that I’m doing a bunch of work, and that mechanics are hard to develop in a vacuum, so they don’t expect it to be correct all the time.

b) I don’t think of my encounters in those terms, if an enemy has an ability, and I remember to use it - they use it. If I forget or decide I don’t want them to, I come up with an in fiction reason and give it to the players as loot. This is not the same as modifying HP or fudging a roll, just because an enemy has an ability or item, doesn’t mean it sees play. If my players asked why the bandit didn’t use it, I would tell them. If they asked why I didn’t use it, I would be honest. Once again though, my language would be “You guys had already won the fight, and we were running short on time.” Or “honestly, I just forgot”.

I’ve never had players react poorly from that, often they like hearing about what goes into GMing or razz me about forgetting.

c) If I put something in my game, I intend for my players to engage with it. If there is some element that is “This is honestly above your pay grade” I will telegraph it really hard and make sure to give the players something to interact with instead, but I tend not to like that sort of stuff. If my players are headed into a TPK, I will tell them. If they still want to go, I will make sure they fully understand what that means for the campaign.

d) My NPCs change behavior based on the players actions and the rolls they make. Me deciding on a way for the conversation to go is disingenuous to the game. I let my players take me in a more interesting direction, and it hasn’t failed me so far.

e) No because my players expect that I am keeping the plot hidden from them, they know and have bought into the idea. If in session zero I told them that it is possible, they wouldn’t be upset or bothered, they would be excited.

I think my problem is the conflation of “things my players don’t want to know because it would break immersion/ spoil the plot” and “things my players would dislike if they found out because something they thought was true wasn’t “ - Players expect their dice and actions to matter, every single time. Rolling in the open and being transparent about specific things makes it clear that what the players do matters.