As always in wartime, take claims made by the combatants with a grain of salt, if not a salt tablet. That being said, it is clear that: (1) the Russians are losing vast amounts of material in this offensive, and (2) most of it is being lost due to Russian ineptness, not Ukrainian prowess. The Russians have a lot more material, and men, and a tradition of fighting this way, so they may muddle through in the end. But the cost is appalling.
NSFW NSFL Russian AFV with dismounts riding on top explodes near Ukrainian trench (11 days ago)
The Russians are not really inept, it’s just they still adhere to the old Soviet battle doctrine. Russian commanders are not allowed to take the initiative or otherwise deviate from the plans set by the General Staff in Moscow.
The Ukrainians know the Russian battle doctrine inside and out, and that’s why it’s easy for them to counter it.
Here we are 621 days in an operation that was only supposed to take three weeks, and Russia really has nothing positive to show for it.
But the Russians have always been overly optimistic. Just look at the “Seven days to the Rhine” plans they had.