Note that capturing a live Russian soldier is worth 10 times more than killing one. Think about how that affects the incentives of Ukrainian soldiers. Avoid committing war crimes, get better gear for your team.
1. Even in the insanity of war, there are rules and ethics we collectively agree to (except Israel apparently with white phosphorus use). I find that gamifying taking human lives crosses the line.
2. Not every captured soldier of course, some don't even know where they are.