Russia knows the terrain very well
That doesn’t really matter when you’re fighting block to block in a very dense urban arena. A lot of the attackers advantages get taken away in situations like this. You may still advance but it’s really going to hurt. There may not even be a real cordon set around the city or any blocking positions adjacent to the assault.
I think we may see (depending on if the world is still able to watch) a change in the kinds of units assaulting the city. More mechanized infantry, more heavy spetsnaz, and more Chechens, etc. all having to bash their way forward figure it out on the fly (Urban combat in a nutshell). In the most extreme urban fighting every inch forward can feel like a victory in itself. Hopefully something can halt this shyt until tomorrow, maybe a little more embarrassment will help bring Putin and his cabinet to the negotiating table.