Well. That was odd.
Russian boosters /trolls /bots are saying this is Putin playing 4D chess. Clearly us mortals are not understanding that looking incredibly weak by granting immunity to the leader of a mutiny is strategic genius. Or pushing another, completely opposite, narrative that it is the the work of NATO dark arts. Of course both narratives are bollocks, not intended for anyone but the most gullible to believe but to cover social media with so much bullshit that the truth becomes buried.
Prigozhin was having his private army taken away from him and being attacked by his own side into the bargain. I am guessing he felt he didn't have much to lose at that stage. And probably was far more successful at marching on Moscow than he had ever thought. But the Russian armed forces were just sitting on their hands unwilling to get too involved either way, and Prigozhin wouldn't have been able to win a fight in Moscow without them.
Ultimately, Prigozhin is a mercenary. I would imagine he has cashed out big time from the Lukashenko negotiation, probably with an agreement about future resource control in Africa (which is where his real money is made). I suspect he is hoping he lives long enough to enjoy it.
If Putin wasn't going to get any help from China for his Ukraine war, he certainly won't now. The China administration don't like a loser. And the CSCTO members weren't exactly falling over themselves to help Putin either. Internal matters etc. etc.
I think Putin will remain in power for a good while longer, not least because there is absolutely no-one in a position to take over. But the whole edifice is looking shaky and chaotic.