Some osint guys have been buying satellite images to carefully inspect russia's vehicle parks and carefully count what is left, the model and the condition it is in.
Excluding 1100 total rust buckets, there are only 3657 tanks left, mostly t72s or older. There are no t90s left.
Of those only 700 are in decent condition. 1100 are in bad condition, such as missing turrets, and the other 1800 haven't been maintained in years and would require a major overhaul to get working again.
IFVs are in a worse place. Only 5-600 bmps remain, and all but 5 are bmp1s or variants. And only 100 brdms or variants. Given they are losing 5 bmps and 1 brdm every 2 days, it is little wonder they are resorting to other means to move troops.