In general, this is the case. I once decided to take down skeletron prime and then I noticed that his head looks different, namely straight from the Master mode, even though I am currently playing in the Expert + Revergence combination (although I myself am in the Master + Death didn't play, so I could be wrong). And after I stripped his hands, I noticed that some attack patterns were missing. All the details are in this video.
I apologize in advance for the recording lags, my PC is relatively weak.