I mean, I don't think the war in Donbas was "genocide" by most common definitions. It was the reckless slaughter of a minority group, and that's borne out just by looking at the magnitude of civilian casualties. imo the argument for invading on behalf of the breakaway regions is not that those regions were being subjected to genocide, but that they should be entitled to self determination in response to ongoing cultural repression, and if Ukraine is going to try to then surpress them militarily, Ukraine should be suppressed militarily (while trying to negotiate for peace, of course).