Please attempt to reinstall the game if it is issues with the sprites and not anything related to your save file.
I've attempted reinstalling from different mirrors, as well as going back to a previous version (v9). I did find after comparing versions that in v9, trainer 141 and vsTrainer141 are the image files for the old nb player, whereas in v12, trainer141 are now the image files for a non player character (with the new nb player character I'm playing now directed as Trainer 5). I figured it was an issue with the save moving to the newer version and looking at the wrong files.
edit: I do want to stay as the new nb player with white hair, my game just really doesn’t like version changes