Question I want to know how many Russians still working in Plesk support and have access to the customer's servers.

[magicnation]

I think Plesk support at least needs to let the customer know/choose who will access their server with full control. Especially for those people who are still in Russia, nothing wrong with the Russians, but the government.
The worst way to find out who they are accessing your server is via LinkedIn. I hope Plesk can do something and act quickly.