Check out this interesting video of a Ukie battalion commander. His frustrated speech clearly shows the following:
1) The basic Ukie tactic: choose a spot on the map, hammer it with artillery fire for a few hours and then send in soldiers as canon fodder to "mop it up". What is important to understand here is that well-trained military forces know how to dig in an protect themselves from artillery fire. Proof: the Ukies surrounded by the Resistance in the "southern cauldron" managed to survive *weeks* of very heavy Novorussian and Russian artillery fire and survive (even if with lots of casualties). So if *weeks* of artillery fire cannot wipe out a force in more or less open terrain, a few hours will not wipe out a well-entrenched force. Another example? The long stance of the Resistance forces in Slaviansk. The fact is that in an urban environment you need to send in very well trained urban assault teams. Just bombing will not do the trick unless you use FAE (fuel-air explosives) munitions, heavy flame-throwing systems like the TOS-1 or tactical nukes. What the Ukies do seems to shoot enough artillery to kill civilians, but not enough to meaningfully degrade the Resistance forces, and then send in the infantry to supposedly "mop-up" an urban area which is full of well-entrenched high-quality Resistance forces. Hence the huge losses on the Ukie side.
2) Noticed his comment about the BMP's main gun stopping after 15mins? The BMP's gun is one of the most trustworthy ever made and there is only one thing which can explain that kind of occurrence: gross neglect of even minimal maintenance. That is also telling of the condition of most Ukie equipment: old and not maintained.
3) Morale: in such circumstances it is not surprising at all that Ukie morale is at rock-bottom. Nobody wants to die in stupid operations, under-trained, under-fed, under-protected - neither conscripts not pros. I have yet to see a video showing some good morale on the Ukie side. Conversely, I have yet to see a single video showing poor morale on the Resistance side.
Botton line: the Ukies are in a terrible situation which is only getting worse.
See for yourself this interesting video: