This has always been overblown and clearly that “many” was an insignificantly small portion of the population once the rubber met the road. Just because you have a favorable opinion of the Russian government doesn’t mean you’re going to suddenly start singing the anthem when their tanks cross the border as they bomb you/your friends (who according to Putin are all probably Nazis) out of nowhere.

So many left after all this so Ukraine’s sympathetic-to-Russia population will no longer be significant by any metric. Putin knows this. He’s lost Ukraine forever if he doesn’t make them surrender.