it's not that you / me makes more mistake playing higher rated player, it's because people rated same / below you / me don't know how to always punish the mistakes / blunder that we make
playing against a much higher=rated players

Hi, everytime i play someone who is higher rated than me i make many mistakes or many blunders even...i dont know i feel somehow tensioned and my confidence is low. I think i should be more focused and give my best to beat them...even though i am not totally a newbie. I wish i played to my best of my chess abilities when playing these guys .
well, that wont do much when playing online

depends on what the intention is. IF your goal is to win or draw said player, you may slightly change the way you play (for example, play more solid and hope to lure impatience, or play in a way your opponent doesnt do well agaisnt etc).
But if what you are asking is about how to deal in general with stronger players at a psychological level, i suggest you become fearless.
1. see every game as a learning opportunity and play the board, do not get nervous or excited because of factors outside of it like "OMG im winning vs someone 300 points stronger than me" or any of that junk. For example, i love playing GM's because the psychological pressure is on them to prove their superiority whereas i play with hunger trying to show my best, (and also risk losing so few points for the honor).
2.realize that you both have the same board in front of you, and play to what you can see or intuit. Dont start playing safe and passive because you are scared your opponent will outplay. suboptimal play will pile on and he WILL beat you if you play like this, or at best leave you in a moribund position and grind you to exhaustion.
3. if you are strongest fish in the pond, you are in the wrong pond. Always seek stronger players, preferably 100-300 points above you.
4.develop bloodlust. This is one of those skills you learn to develop with experience. You have to want to win and check every resource at your disposal. Against a stronger player, playing in this state is the only way you wont get lazy, (and agaisnt said players, sloth is death). This is also good advice for people that get stuck and start plateuing in cruise control in the game. make playing strong players and the adrenaline that comes with it work in your favor. This will crystallize with more experience.
5. Do not prematurely accept draws. Long term you will benefit much more earning your win or lost and if the latter , letting that trauma burn in your neurons some lesson on what you did wrong on the board, then getting lucky with a 0.7 position, and accepting a draw to brag like a fool. This behavior on class players that claim they want to improve infuriates me. If its often a symptom of lacking bloodlust but it could just as easily be 1, or some rationalization.

Hi, everytime i play someone who is higher rated than me i make many mistakes or many blunders even...i dont know i feel somehow tensioned and my confidence is low. I think i should be more focused and give my best to beat them...even though i am not totally a newbie. I wish i played to my best of my chess abilities when playing these guys .
It's funny you say that, I have the opposite problem- my best games are against higher rated players. Against low rated players like myself I feel like its embarrassing to lose and then I pressure myself or get angry and make mistakes. Against high rated players I feel like it's fine if I lose so I stay calmer and play more logically. I feel like I am stuck in a low rating rut where players play chaotically and can catch you off guard.
Open with English or reverse sicillian against an 850 and they will do something weird like ram pawns forward or bring a rook out early. Play it against a 2000 and the game plays out like a Ben finegold video- the move order becomes logical. I feel like its tougher playing low rated opponents because it's always chaotic.
Hi, everytime i play someone who is higher rated than me i make many mistakes or many blunders even...i dont know i feel somehow tensioned and my confidence is low. I think i should be more focused and give my best to beat them...even though i am not totally a newbie. I wish i played to my best of my chess abilities when playing these guys .
It's funny you say that, I have the opposite problem- my best games are against higher rated players. Against low rated players like myself I feel like its embarrassing to lose and then I pressure myself or get angry and make mistakes. Against high rated players I feel like it's fine if I lose so I stay calmer and play more logically. I feel like I am stuck in a low rating rut where players play chaotically and can catch you off guard.
Open with English or reverse sicillian against an 850 and they will do something weird like ram pawns forward or bring a rook out early. Play it against a 2000 and the game plays out like a Ben finegold video- the move order becomes logical. I feel like its tougher playing low rated opponents because it's always chaotic.
wow!!! you are like me! I play better against high rated opponents, my 5 best wins on lichess was against 2500, 2400, 2400, 2300, 2300 players, and my rating is just 2000.
I think players in 1800~2000 are 'club players' or 'cafffe players'. They are concrete, play for win and dont care about strategic/positional ideas. The postion turn chaotic and for punish theirs mistakes is necessary time. In blitz we dont have time to analisys postion details and calculate concrete lines. Chaotic postions are bad for strong players too... For example, pawn endgames are hard do calculate and strong players preffer maintain rooks until they are exactlly what is happening!
The lack of logic is simple: weak players are gambling players... I like to say in chat sometimes: oh, come on, you dont know what are happening, you are bet just...

Think about it. How could the game show that the other player is better? It NOT like in poker where the result of each round you either win or lose and then see an average win rate. Every move has a calculated value so the moves the better player makes should be more frequently the correct moves for any given positions, or at least they’d be close runner up to the best move. That also means that to win or draw from a player you have to (whether by guessing or calculating) have values of your moves closer to theirs. But since both players already have a calculated rating based on past games we can conclude that regardless of your perception of the moves you see your moves on average are going to be worse. Not necessarily that they’ll be blunders. They can just be 2n, 3rd, 4th...nth beat move, but with time the opponent will have an advantage as the difference in move value adds up.
Hi, everytime i play someone who is higher rated than me i make many mistakes or many blunders even...i dont know i feel somehow tensioned and my confidence is low. I think i should be more focused and give my best to beat them...even though i am not totally a newbie. I wish i played to my best of my chess abilities when playing these guys .