They did, because either they didn’t have criminal charges against them yet, or were smuggled out of the country illegally.

If you have criminal charges against you in Russia, you can’t get out. And at this point you can be sentenced to 5 years for “discriminating the army” if you write publicly in a social network that you are against war or that there were war crimes. Many people who did are already in jail, others will be detained if they attempt border crossing.

You'd first get administrative charges and a fine. Sometimes you can even fight off the fine in the court -- I personally know someone who did.

After that you either shut up or leave the country, which of course is very bad.

They just reinstated крепостное право, now one can't leave the country if a military recruitment office (военкомат) sent a summon letter (even if you don't receive it. You have to check yourself manually on a special website beforehand). Along with other restrictions like ban on transactions involving real estate (land, apartments, houses) and such.