Do you care to list those sources? It sounds exactly like a successful work of Kremlin propaganda.
Please, ask anyone, any foreign citizen who lived in Ukraine, if they ever saw people like that in person and if it was anything but a short "demonstration"/provocation happening once a year.
Banderites (followers of Nazi Stepan Bandera) are all over Ukraine in significant numbers. The current President Zelenskyy constantly talked about them and their growing support over the last decade in his comedic performances and as a politician.
Western media is suddenly reluctant to discuss this history (possibly because of state objectives) but the articles and other news media produced from ~2014-2016 on this topic are easy to find.
>The current President Zelenskyy constantly talked about them...
I was impressed about the way his silly rethoric has changed in the last 2 weeks (or really last one year). He is a different person now. Go and ask him about any of that nonsense now.