hmm thats the 2nd time someone mentioned this happening, but I havent been able to cause it myself. I do think its related to the alt skins.
My mind was very deep into strat in that moment, so I'm not sure what I did, but I have the habit of evolving and pressing the "continue" icon to go to the new tile of the run while the monster is still evolving, sometimes. Could it be related to that? Is there some weird stuff with the animation? Dunno, just throwing hypoteses out there owo