IMO, Prighozin needed more support to continue the movement towards Moscow. When Kadyrov announced full support to Putin, the chances of Wagner succeeding went way down. Large segments of the Russian military not switching loyalty was also a nail in the coffin. Wagner took Rostov and the surrounding areas without much resistance because the civilians and soldiers there know the war is going badly, but the further away from the front they get that’s not the case. Wagner was getting more pushback the closer they got to Moscow.