Prigozhin is probably upset about the war in Ukraine because it isn't in their interests. They are PMCs, mercenaries. They have no interest in fighing a long protracted war and suffering large-scaled casualties for little gain either politically or monetarily. He also likely smells blood in the water, Putin is in the weakest position he has ever been in as we talk abou tthis even.

Wagner in contrast whilst suffering is in ascendancy. They are the strongest and largest they've ever been and seem to be doing a lot of heavy lifting in Ukraine for the Russians. So they're disastisfied but also seem to have the means to do something about it.

They'd much rather be deployed to fight the more conventional wars that Mercenaries fight these days in the global south. And as long as Putin is in charge there is a good chance Wagner isn't going to get back to fighting those wars. So it would make sense that they mutiny.