If he was Ukrainian, we’d be told that was Nazi flag.
Well, the founder of Wagner, Dmitry Utkin, is an actual Nazi, with Nazi tattoos. He selected the name because Wagner was Hitler's favorite composer. Wagner still has plenty of Nazis and still uses Nazi symbology. Some of their units are straight-up Nazi, like Rusich and Zimargl groups and led by Nazis (like Alexey Milchakov). Here's their Wagner unit patches.