Thanks for the reminder and the historical perspective that entails.
In this particular Ukr Rus war/SMO the casualty figures have been endlessly debated in alt media. The usual suspects like Col Macgregor, The Duran and many others. This, using the combination of RF released statements and evidence presented elsewhere.
RF seems to have relatively accurate data on Ukr casualties since they rely on listening to mil comms traffic after each battle.
Even the BBC was getting closer to admitting the horrendous Ukr KIA score via their (Lithuanian? based news outlet which counts via Ukr obituaries). Although this must be an undercount since lots of Ukr KIA are left on the battlefield, partly due to corruption of Ukr officers, and secondly from the motive that bereaved families will not be paid by the state.
As to RF reported casualties, these are evidently relatively low. People, like Simplicius, point out that RF social media is still alive and well and if the RF KIA etc. count was higher than officially reported, this would be easily exposed.