Yeah. Breaking agreements isn't okay "if you don't get caught".
My preference is that if the GM is going to do that, they tell me. Doesn't mean they have to say on each occasion it happens, just "yeah, I will do this as part of the game on occasion."
I see literally no downside to this.
100%. There's a semi-dysfunctional game style where the GM pretends they're not railroading, and the players pretend not to notice while they're fully aware of what's going on.
I've literally had people in games tell me "come on, let's just start the fight, it's obvious that's what the GM has prepped".