For Russia (and many Russia apologists) Ukraine is not an innocent neighbor or not even a neighbor in the first place (not a "real country", part of mother Russia, part of the empire or part of the legitimate sphere of influence, legitimate by destiny...), and Russia is liberating Ukrainians from their current leaders or at least liberate the Russian speaking subset of the population.
Clearly if you're not sharing this worldview/framing it seems clear that Russia is just paying the obvious consequences for their actions, and that they are morally on breach of contract.
Unfortunately in practice the contract doesn't matter. There are no courts, there are no normal arguments to be had here.
Russia made a choice and are bearing the consequence. Other countries made their choices and are bearing the consequence.
Some gambles have been made, some have failed, others have not yet played out fully.