One that I vividly remember because I tried to mediate it was the edit war over the name of Pristina (capital of Kosovo) - whether it should use the then-traditional phonetic English spelling "Prishtina", Latin Serbian "Priština" (either with or without the diacritic), or Albanian "Prishtinë". It got bad enough that at some point the article used double naming throughout.
I visited Catalonia once fifteen years ago, and so for a while I had an interest in Barcelona and Catalonian topics such as Antoni Gaudí. Now, I knew about the Catalonian independence movement, and the history of oppression by Franco and so forth. So it was no surprise that the nationality of Gaudí was controversial. If you put that he was a Spanish architect then someone would soon come along and change it to "Catalan architect" and of course, that could not stand more than a few days before a nationalist would change it back to "Spanish". So we compromised on "Antoni Gaudí was a Spanish Catalan architect", and this phrasing withstood most scrutiny, and we managed to tamp down the edit-war on that particular lead sentence.
Other nationalistic edit-wars of note include the naming of the FYROM (Macedonia and "North" Macedonia), Armenian genocide denial, the Israel-Palestine conflict, of course, and many many others.