Question Author
"Wagner is a mercenary force. Mercenaries are paid to fight. My assumption is that Putin/Russia was doing the paying. If so, why now has Wagner switched sides and who now is paying? "
Wagner aren't really mercenaries as such, although I referred to them as that. Mercenaries are people hired by an army to fight for them. Wagner is probably in effect a series of companies funded by criminal activity around the world, notable in Africa. They have it is suspected been used by the Kremlin to do it's dirty work there and in the Middle East when it suits the Kremlin to deny direct involvement.
During Russia's war on Ukraine Prigozhin stepped in to recruit prisoners by the tens of thousand to bolster the Russian army's flagging manpower. These recruits were largely used in the assault on Bakhmut (Donetsk region) to create human waves of cannon fodder, drawing Ukrainian fire and exposing their positions, before more competent forces would then engage their enemy.
Tensions have come to a head since Wagner withdrew from Bakhmut, with a war of words - most of them coming from Prigozhin - denouncing the Kremlin's prosecuton of the war, with Prigozhin claiming that basically the main army were useless without him, and bemoaining the sacrifice of so many of his dead men (pretty appalling hypocrisy really given these were Progozhin's own tactics).
Recently the Kremlin announced that it would be taking over the issuing of Wagner's military contracts, to which Prigozhin responded defiantly.