The Ukrainians are claiming 360K+ KIA.
Casualties of Russia in Ukraine - official data
I believe this number includes Donbas conscript and Wagner casualties. There are a lot of other estimates out there ranging from ridiculously low to around this number. A lot of the western analysts assume KIA to wounded ratios that IMO are unrealistic for the Russian army. Because of this they get much lower KIA numbers.
Western analysts can't get their head around just how primitive Russian field medicine is. They are barely up to WW I standards. The Ukrainians aren't to US standards which is insanely good. For recent US wars the wounded to KIA ratio is around 10:1. The Ukrainians are able to achieve about 5:1, and possibly 7:1 which is better than the US was able to achieve in Vietnam.
I have seen some in depth analysis of how the Russians treat their wounded. Frequently they don't make any attempt to rescue the wounded and let them die on the battlefield. Russian field ambulances have been captured full of ammunition. Their field hospitals are poor, their first aid kits are almost non-existent and what does exist is out of date with deteriorated rubber and moldy bandages. Nobody gets medic training so nobody knows what to do to stabilize anyone who does get hit. Only the lightly wounded who are able to get themselves out or a few who happen to be near medical help when hit (such as in a read area) survive.
The analysis came to the conclusion that out of ever 5 Russians hit, three die, or a ratio of 2:3 wounded to KIA. That makes the overall Russian casualties around 600K with about 360K dead. I read the analysis about 6 months ago when the casualty numbers were much smaller, but those would be the numbers with the current reported death toll reported by the Ukrainians.
The ratio may be skewed even further towards more deaths now with the Russians resorting to meat wave tactics.
The Russian tactics are not only horrific, but they are also stupid. Russia has a declining population for decades. Their workforce is aging out. They are facing a demographic cliff in about 10 years where they will have too many retirees and too few people of working age. Taking 300-500K workers out of the workforce permanently between KIAs and badly wounded will just make the demographic hit worse.
Russia only had about 8 million men between 18 and 40 at the start of this war. These men are needed to work in war industries, keep the civilian economy going, and fight the war. Tying up a lot of them in the military is already bad, but getting a lot of them killed is just compounding the problem.
Paraguay fought a disastrous war in the 1860s. I don't think Russia will get anywhere near as bad as Paraguay, but in that war something like 80% of the male population died (scholars disagree on the exact numbers). But Paraguay has not recovered from that loss 160 years later. And Paraguay's population was growing rapidly at the beginning of the war, not declining like Russia's.