Interesting reports Russia has mobilized at least a moderate number of latest T-90M tank forces both in Crimea - that recently came over Kerch bridge to reinforce South (with active tank training ongoing now in Crimea) and now new photo confirming at least 6 in Belgorod close to Ukraine, presumably on way to reinforce or counter-attack at collapsing Luhansk front.
I would note Oryx has only seen 3 visually confirmed kills/captures of this latest T-90M model - out of 1240 odd tanks lost by Russia so far. So the best of the remaining Russian tank army appears to now be mobilized. Whether a last gasp, or the core of a significant new offensive drive, remains to be seen. Russia was thought to have ~100 of these latest tanks pre-war, so overall could be a fairly large armor reinforcement for a new offensive - if Russia can crew and supply them up to the front with proper support.
But Russia has to have gutted the last of their reserve armor divisions to field these...