Those people could be Polish or Ukrainian or born somewhere completely different
They have russian state-specific latin names transliterations Except for Roman Tsisyk, there's nothing specific in name.
But most probably the guy from moscow got caught with russian ip which busted the whole gh organization. I don't think gh has any other sanctioned regions users id methods
Microsoft is a US based company. They cannot legally make business with sanctioned entities. And since it's not profitable for them - they just made a geoblock geoblock
Could MS ignore the sanctions in that case? probably