Here's a realistic number:
https://meduza.io/en/news/2023/02/13/mediazona-and-bbc-news-russian-publish-further-figures-on-russia-s-losses-in-ukraine
Mediazona and BBC News Russian, together with a group of volunteers, have confirmed the deaths of 14,093 Russian servicemen killed in the Ukraine war before February 12. They arrived at this total using only public records and other open sources.
Public(Russian) and open sources?
Well then I guess that’s that