I am not aware about this but STEX is a KYC-required exchange. It is why I stopped using STEX since the day they required KYC mandatorily.

If do reject to process withdrawals for customers from Russia or Belarus, I guess it is related to sanctions from EU on these nations as part of responses against the war in Ukraine.

I searched and got the article in March Sanctions only traditional finances or crypto world too ?[url]. You can say it is fair or unfair but I disagree to call STEX is a scam exchange.