It's not "human waves" in Ukraine, it's advance by attrition in Ukraine, as JumpCrisscross pointed out above. The Russians have not considered themselves limited by causalities, while the Ukrainians have to conserve manpower and materiel. So the Russians can "afford" to throw a bunch of squads out along a front, and if 90% or more are casualties, they don't care, so long as they can take some ground. Then, once they do, they rinse, lather, and repeat. It's a hideous expenditure of human lives, but it has worked tactically. Whether it is a significant gain operationally or strategically, I don't know. (Russia is going to pay a price down the road for losing all those young men, but it won't be paid by the old men sending them to their deaths.)