https://meduza.io/en/feature/2023/07/10/bring-out-your-dead
Meduza and Mediazona used probate registry records to estimate the total number of Russians under the age of 50 killed in the war so far. By their estimates at least 47k Russian soldiers under the age of 50 have been killed with a casualty count of at least 125k through May 2023 (this doesn't include soldiers who are missing in action or captured soldiers or soldiers from the DPR/LPR- these are likely to be in the tens of thousands).
To put these losses in perspective these are three times more deaths than the Soviet losses in Afghanistan over ten years. Nine times more than the first Chechen war. And keep in mind these are an undercount.
The methodology was cross-validated with excess mortality data and with obituary data to account for not every soldier leaving behind an inheritance.