Yeah, the whole “they’re not sending their best” Spiel was debunked in the first 6 months. The Russian equipment losses favored high end stuff at the beginning of the war and has been declining ever since. And the Russians have been activating older stuff ever since. Which is visible in the loss data.
A lot of conscripts are indeed not in the war, but judging by performance of the Kursk defense, there is reason to doubt the ability of these forces. Although quantity is a quality by its own right.