Lots of Ukrainians live and study in Russia even after the war (I knew a Ukrainian citizen who was studying at PhysTech despite the 2022 war), and lots of families in Russia have relatives in Ukraine (and vice versa).

It makes this war even more tragic, because Ukraine and Russia are so intertwined socially and culturally, and there was no reason for Russia to escalate the war.

That said, Roskomnadzor can't fully lock down ingress and egress without drastically impacting the Russian economy and pissing off your average Russian who watches YouTube, games on Steam, and messages using Telegram.