hey sandro. when i first read your posts I thought you were a more advanced player than me but I guessed wrong *no offence* im also a penhold player trying to improve and u also have a coach and I know sometimes it feels good to get some advice from others too so I'm gonna try my best to analyze your video

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while it is true you should not focus on your wrist movement for now, try getting more wrist only on the serves. don't use your wrist for pushes and other things (for now)
I also saw that in your backhand serve you did not cut the ball you just gave it a flat hit and it went on the net. you should work on just one of your serves for now.
you also need to fix your forehand form it looks really weird and its putting you off balance
your legs are also all over the place you aren't keeping them wide enough and you aren't bending down enough
also you bend your body away from the ball when doing forehand. its something even I did while I was pretty new to the game. just do more multiball training and single ball training to improve it.
i noticed that your elbow is going up with your racket while making forehand shots.
dude just look at some players practicing forehand and ask your coach to guide you to fix your forehand.
when you use your backhand you are keeping your racket angle the opposite way that it is supposed to be. idk how to put this into words but try putting pressure on your index finger and keep your thumb at the handle while doing backhand.
also I think you should switch your rubber Volant Phoenix rubber is generally not considered suitable for beginners so try out something like xiom vega x or xiom omega. just use some slower europian rubbers for now