Are you joking? Russia has thrown everything it has at Ukraine for quite some time.

Russia is throwing most of its deployable conventional firepower on Ukraine and whatever robots, KABs, missiles and drones it can manufacture. It is their manufacturing capability which is limited.

Have you seen the Oryx list of destroyed equipment? The defunct Soviet Union produced a shitton of armored vehicles, Russia inherited most of them and they all got burnt in Ukraine.

In which way is Russia being soft on Ukraine?