I think there's a far simpler explanation; genocide. Putin has been throwing Chechen conscripts into this meatgrinder at a pace which shows he has zero issues whatsoever with any level of casualties. The losses are a feature, not a bug. This is Russia, not Iran. They have reserves of over 10 million troops to call on, and the worlds largest inventory of military equipment. He knows he can just throw bodies at this and avoid losing the expensive aircraft and pilots he will need for his coming showdown with NATO.