Guys thanks for all the help! I am located in Greece, english is not my mother language so i have difficulty explain th situation. Let me clarify some things. There is no play, anywhere, crankset,bb, chainrings everything is tightened correctly. BUT if i observe the movement of the big chainring inside the derailleur cage i can see it move 1 or 2 mm outwards, so chain is rubbing the outter plate of the derailleur, when my left pedal is between 2 and 3 o'clock. Thats why i suspect that either splines are damaged as said before, or powermeter bolt holes are bent in some way. I dont know if i explained it correctly.
Ps1: I appreciate the time you put on this!