I’ve been using yandex as my open-source/public/spam-heavy email provider for a handful of years. Ignoring the current conflict, the yandex product is pretty good. Their search is, IMO, second only to Google, at least for technical queries.
Edit: probably going to just buy a domain and protonmail as a contingency plan, though. Don’t want to lose access.
Sadly, search quality for “the rest of the world” has been neglected for years, and it's a miracle yandex.com still works. Mail is one of the services that is kept up to date, with translations and stuff, and it's nice.
As for the global issues,
a) Iron curtain for the Internet (i. e. absolutely everything not working properly) would be a sure way to get every commoner, currently soothed with entertainment, on the street.
b) This won't last long anyway. I would be more worried about sudden drop of funding and technical issues.
If whatever handful of things are your most used sites/services/etc online were shut down tomorrow would you consider it the end of the internet for you? You'd (I guess, at least I would) immediately move to the next best (maybe even discover it's better!) or wait for a competitor to spring up.
So there's a huge difference between those few platforms blocking Russia but a whole world of alternative ways to spend time online vs. only domestic Russian options.
Definitely consider migrating off Yandex. If (when) it will be required by gov to choose either staying in russia or outside of russia, it will choose the former.
I made the mistake of posting an email address on HN. I get a lot of spam on it now. I know it's because of HN because the email address is hackernews@domain.
Edit: probably going to just buy a domain and protonmail as a contingency plan, though. Don’t want to lose access.