From what I understand the Russians treat their pows decently well. They follow protocol as outlined by the UN charter, so it’s not like they’re executing people outright or anything. The main thing is the Ukrainian army is in retreat and historically that is the point where you will see the highest casualty numbers because you are losing the cohesion needed to actually mount a defense. Not surrendering is essentially suicide at this point because you might live through one Russian breakthrough, but there is no guarantee you’ll make it through the next one or the one after that. It’s a long way to Odessa.