Scampir

game 1: i strongly suspect that the player either (a) has been badly burned in the past by "railroading" gms and is reflexively trying to preserve their agency, or (b) thinks the gm SHOULD be railroading and it's just playful teasing to strain against you with the belief that you can and will "win" and make the planned campaign happen.

game 2: i have heard that in some older schools of play, there's no in-character path to knowledge so you have to rely on player knowledge; it's possible the player just doesn't get that everything will be okay or is otherwise struggling to switch paradigms. alternatively, it could be that they believe the lore won't affect gameplay much, and is therefore a safe or consequence-free arena for playful teasing.

in both cases, the solution is the same: have a conversation where you establish explicitly why they do these behaviors, and explain that it's not fun for you and is souring the experience despite their intentions. (and if it's because of their own discomfort, like the railroading thing, offer concrete steps to address that going forward.) if they blow off your concerns, go to the next stage: "either the behavior stops or you're out of the game."

good luck!

@unboxedcereal has the right of it. What I'd emphasize doing as well when you talk to them is just like, telling them how doing this makes you feel: stressed, fun-sucked, etc. If they persist beyond that, you can only assume that they like. Don't care and you can safely give 'em the boot.

A GM is a player too. If one player was actively shitting on another's parade then you'd have something to say about that, right? They don't get to do that to you without your consent either.

I came here to say exactly what the others said, so having a chat, establishing boundaries/consequences, and doing the painful work of holding to them sounds like your best bet...

I've had three problem players in my time. One refused to ever engage with the story I was trying to build, even whennit incorporated the stuff he said he wanted for his character. It was exhausting to set stuff up for him only to have him knock it all down because it "wasn't enough." Eventually, I even had his character's god show up to explicitly tell him things and he still refused to engage/believe. I had to go on a walk after that one and the whole table basically had an intervention for him because nothing I'd done had worked. If I knew then what I know now, I'd have tried to talk to him about it more outside the game rather than handling it all before, during, or after game time (we were in college and played from 3pm until ??? On fridays, so there were a lot of breaks).

More recently, back in 2021, player crossed one of my lines during a session and I gave him his 1 warning (which stung extra bad because we'd just reviewed them in another game I ran that he was in). He also tended to brush off hurting other player characters with his AoEs as "it's just HP" despite the group being super heavy into the roleplaying side of things and then offered to let the aggrieved PC beat his character up to "make them even" after I pulled him aside about that. The last straw was when we were doing some exploration and the party wound up getting caught in an on-coming prairie fire, which I'd warned them about repeatedly and even done the whole "here's what that would look like in terms of damage and checis and since one of you rolled super high on your survival check, here's a government handout on how to deal with prairie fires" the session before. This player, as the fire got closer, wound up catastrophizing the whole thing and getting so loud and frustrated and upset that he'd interrupt the other players. I had to kick him out of the group thay that point because he wasn't learningnfrom our talks or even trying to change hos behaviors. Which was especially awkward because I'd been his person of honor in his wedding a year and a half prior...

The last one was just a meta-gaming, ubcooperative player who refused to engage with the fiction and just played d&d as a numbers game. Every time I'd talk to him about trying to engage eith the story and the stuff we'd talked about for his character, he'd seen super excited but would still never actually engage with any of it. That one was a bit easier because no one really wanted to play with him anymore and there was an unrelated tpk around then, so he just didn't get invited back to the next game.

I've kicked out 2 other players in my time, but those where for other reasons. One turned out to be a Joe Rogan/Jordan Peterson alt-righter in development and the other one... well, is a much longer story but amounts to him being unsupportive of my indentity in a way that made me unwilling to do the vulnerable work of storytelling with him beside, of course, me no longer having fun when I'd play with him.