You need to understand these types of territorial disputes and blood feudes don't get formed in an instant or over one single event. For all the Serbian sabre rattling of "KOsOV jE SErbIa" ethnic Albanians in the region have been contesting Serbian rule since at least the 12th century when they became a breakaway principality if not before that. Catalonia has constantly gone in and out of an autonomous state, trying to seperate from Spain. Crimea again, theres been lots of back and forth and legitimate hostility with the rest of Ukraine.
If these conflicts and seperatist movements just appear out of nowhere with no prior history then it's 100% glowie manufactured horse shit. It's not hard to lead someone who is poor, hungry and stupid by the nose, and Ukranians were and are all three of those things.
In regards to Transnistria, it was purely a political matter. Most of the soldiers stationed there and the administration, came from the USSR so it wasn't about ethnicity as much as political indoctrination.