I have experienced video freeze at the first like 20 seconds which fixed after page reload, but many people say that it's impossible to use without VPN
I'm gonna guess it's the authorities. It's usually them. Google is presumably making money off of it and has little incentive to do it, especially piecemeal, while Russia has a history of censoring and often throttling internet access.
Also, Radio Free Europe/Radio Liberty, which is, I should note, funded by the US government, claims that's what's happening [https://www.rferl.org/a/youtube-russia-throttling-tech-censo...]. So it seems quite likely that it is, in fact, Russia's government behind this.
