Getting bluffed out of pots where other player is all in

This frustrating donkish play against me is becoming a major leak of mine.
Usually happens in small stakes but has happened to me in low stake tourneys as well.
Once it was a UK player on Stars who called me all the way when I turned a flush then shoved on the river when the other player was already all in preflop.
I need to be wary of these steal plays as I'm starting to experience them usually on Stars but also 888.
While writing this I busted the player who bluffed me out so that always feels good LOL he had 27 on the button & I had q9 jj10 board he shoved the turn after calling a bet for over pot. I've also seen the min raise or 2X your raise when flush gets there on board these happen ubiquitously.
I find that I generally play way too tight & need to even call much looser as I progress, I find this aspect of playing large poker field tourneys exciting & highly challenging.

I get where you are coming from and it is frustrating as hell. I see it a lot at the lows stakes as well but have also seen it happen at the casino but not nearly as much. All you can do is pick a spot with a decent hand and go for it. Once you have felted them a few times they will stop trying to do this against you as much.

Not much that i can analyze here without seeing specific situations you are referring to.
Generally speaking you shouldnt worry about getting bluffed off side pot at all, until you dont get into tournaments of $530+ (maybe some tougher 215s as well),
This is due to pot being protected by an all in player already, which makes you play most of the time only for a side pot and usually people have same thought process as well.
To rephrase it - you dont need to put any chips into the pot that is not existing.

Hope this helps and Good Luck!

Some of the time it makes sense to bluff when a player is already all-in, which is usually when there is a non-negligible side pot to fight after. People definitely can and should bluff to fight for the side pot in a lot of spots. But if there's no side pot or it's very small, then bluffing doesn't usually make sense.

It may feel frustrating to get bluffed off a winner when there's no side pot, but remember that sometimes you'll be the all-in player who benefits from opponents betting without a purpose in these situations. It feels nice then!

I guess this would be super annoying on the final table. Because having 2 people try to knock out the all in player ladders everyone up. But if it isn't the final table I say it is fair game. Better to bluff one person off and go heads up against the all in, than to play a 3 way pot. Also this gives the player that is bluffing information. If you are calling, he can be pretty sure you are bottom pair or better.