The issue was that the Ukrainians purposefully positioned themselves within cities' civilian infrastructure as opposed to facing Russians head on, for obvious reasons, while Russians (at least in the early stages of the war) had shown significant restraint by refraining from attacking them wherever they were (rather, they expected to quickly decapitate the Ukrainian government.) And no, the Allies' terror bombings of Germany are still a subject of debate among military historians, with significant evidence showing that it had, in fact, crippled Germany's capacity to wage war. In any case my point here is that Russia should have opted for a Shock And Awe strategy, which would have a higher chance of routing the Ukrainian army while preventing them from regrouping with haste.