Comparing the rate of progress Russia is making now with a year ago really shows how much AFU has been degraded in the past year. It used to take months to take a single settlement, and Russia used to do a single offensive at a time for the most part. Now, Russia is pushing on large parts of the front all at once, and they're facing minimal resistance.
It's a clear indication that the AFU lacks the forces to effectively hold territory at this point, and this is going to be a self reinforcing phenomenon. The more territory AFU loses, the harder it becomes to hold the remaining territory because more and more Russian troops are freed up from territories already captured. Ukrainians refusing to retreat also plays into this because they always end up with significant losses fighting for territory that's already been lost.