I think they are trying to make some kind of success out of the failed spring offensive, so there are more on the front line... plus the mid range strike capability is legendary now.

Russia still has many tanks in active service. What they don't have is a lot of tanks in storage that could be put into service quickly, nor a production line that can make a lot of tanks on demand. Russian commanders are thus forced to be careful with tanks because any lost tank won't be replaced. However they still have a lot of tanks and so if they judge it worth the risk they use them.