I just noticed that when a token isn't more or less square in proportions, it resizes oddly/badly in Roll20.
I'm attaching a screenshot in which you can see a few well scaled tokens, and between them the instances of the "black guy" are the anomalies.
Also, this may have to do with the automatic "snap to grid" feature that seemingly Roll20 has (*), because the newly scaled token seems constrained to fit in the hexgrid by force.
(*) I would suggest (maybe in another thread) to be able to enable or disable "snap to grid". Sometimes there are advantages playing with a grid but not with automatic "snap to . . .": for instance, one of the "sword and shield black fighter" appears off-centered because the automatic snap-to-grid that Roll20 currently forces on tokens.