There are both US and EU sanctions on Belarusian individuals and entities, but no broad sanctions that would apply to all developers in the country of which I'm aware. This seems like it might be an error.
Or calculation that it's cheaper to just get rid of Belarus-linked accounts than getting into trouble for a few that are linked to a sanctioned entity.
Yes, seems like it's a crackdown on Belorussians incorporating in Western Europe. My guess is that they looked at it and considered to be a risk. Maybe an incident like oligarch moving money through sham iAP drew attention to it? Who knows.