Tragically a lot Buchas happened[0], and there's plenty of videos of civilian executions - God only knows what atrocities are yet to be discovered in occupied territories.
All for some messed up sense of ethnic superiority.
[0]https://en.wikipedia.org/wiki/War_crimes_in_the_Russo-Ukrain...
You should also look at the evidence for executions of "collaborators" after Ukraine recaptured e.g. Kherson, Kupyansk, Izyum (and, in fact, Bucha, although there is also plenty of evidence of Russian war crimes there).