So nobody knows what's happening, really, but here's some expert opinion:
From Tom Nichols at The Atlantic,
A Crisis Erupts in Russia:
A simmering political feud in Russia has exploded into a crisis. The head of a Russian mercenary army fighting in Ukraine alongside Moscow’s official military forces has declared war against the Russian ministry of defense,...
Think of this conflict not as a contest between the Russian state and a mercenary group, but a falling out among gangsters, a kind of Mafia war.
A government doing a lot of bad things in the world can make great use of a cadre of hardened and nasty mercenaries, and Prigozhin has been making his bones for years as a tough guy leading other tough guys, ultranationalist patriots who care more about Mother Russia than the supposedly lazy and corrupt bureaucrats in Moscow. The Ministry of Defense, meanwhile, is led by a political survivor named Sergei Shoigu, who has managed to stay in the Kremlin in one capacity or another since 1991. Shoigu never served in the Soviet or Russian military, yet affects the dress and mannerisms of a martinet.
...A full-scale civil conflict—for now—seems unlikely, if only because Prigozhin has no institutional base and no major force beyond his fighters, who are a pretty unsavory bunch.
...Right now, none of this looks organized enough to be a coup. But coups sometimes look ridiculous in the offing—the 1991 coup against Soviet leader Mikhail Gorbachev was a complete clown show—so the possibility remains that Prigozhin has friends in Moscow who are working with him.
...So far, tonight’s chaos does not seem to involve the U.S., NATO, or even Ukraine, but a fight among Russian gangsters, in part over whether Russia is being brutal enough in a war of unprovoked aggression, is something to watch.
...no matter how this ends, Prigozhin has shattered Putin’s narrative, torching the war as a needless and even criminal mistake. That’s a problem for Putin that could outlast this rebellion.