Great ... but just trying to understand how it could be.
Flight Controller receives all the info from sensors / GPS / Barometer / Gyros etc. It then evaluates required ESC command to each motor based on this info and pilots command.
Even if a prop is slightly out from the others - the FC would detect the different results and compensate accordingly. The speed the FC does this is in decimals of a second .. faster than any pilot can do and eye can detect.
The only reason I could imagine for a non OEN prop to cause such - would be if it was flexing when FC was adjusting ESC output, causing the blade to change its pitch / thrust enough as rpm changed. That would then cause FC to adjust again and may get into oscillation as the blade flexes.
Question : Your old props - are they more flexible than the OEM ?