If we want to be charitable, they are not referring to Ukraine at large but to groups like Azov, Right Sector, C14, etc..., That are indeed Nazis and that have been armed and trained by Western forces in full understanding of who they were and enthusiastically.
Is Russia used the armies that are currently in the Ukraine to kill all Azov members there would still be objectively more Nazis in Ukraine then before the invasion. Any military force I have looked into has a lot of Nazis and Russia also. Instead of denazification of Ukraine Russia added Nazis on Ukrainian ground by having soldiers invade. The only reason why you aren't aware of battalion names of Nazis in Russian army is that the fact that the presence of Nazis is totally irrelevant for the argument the west is making while Russia argument totally depends on so RT pushes that narrative.
