Ukraine

War rape and other abuses tend to be higher in armies that are experiencing higher-than-normal fear and anxiety. It's why Vietnam for the US, despite being rather middling from an international politics concern, was so filled with abuses - you had a bunch of half-trained scared kids tossed into the jungle with unclear orders, no motivation, and boogeymen behind every tree. Being pressured doesn't excuse atrocities - but it does go some way to explain them. People often react aggressively and irrationally when under pressure.

The situation of Russia here is worse - these half-trained scared kids are being tossed into a somewhat archaic conventional war, meaning that in addition to unclear orders, no motivation, and boogeymen behind every blade of grass, you also have the constant shelling and the ever-present terror of an assault being ordered to keep you pissing your pants. That's not even getting into Chechen blocking detachments and the sheer viciousness of many Russian officers.

There's also the practice of dedovshchina, which is... gruesome, and has created a very brutal culture in the Russian military. It's effectively rape and torture as 'hazing' conscripts, and is something that the NCO corps engages in as well. Obviously this is not a good practice for creating professional troops who are less likely to commit horrific atrocities. It's a great (/s) practice for creating damaged kids who think that rape is a way of expressing superiority and ensuring security in the social order.