So, my question is: how exactly are they going about blocking the websites? Is
it a DNS-based block? DPI and content-based one? Anything else? Any info on
it?
DNS resolution appears fine, based on traceroutes it does not appear to be more sophisticated than address blocking at the international frontier by the few gateway, in the case of Beltelecom near the border routers at 93.85.80.0/24.