David Ellisson apparently tried to make Taylor Sheridan feel at home with the new management at Paramount, but the two had a clash of egos. Taylor Sheridan and his friend David Glassner of 101 Studios were used to not being told what to do. Sheridan practically had the only say on the running of Paramount+, which I understand, because his shows drew most of the streamer's 80 million subscribers anyway. However, Sheridan had hit his peak and even I, a big fan of his, had started noticing a decline in his projects.
Paramount will now retain full control of Yellowstone and all its other IPs, and while it might seem like the end of the road for most of them, you should never underestimate what a new set of eyes can do with an old franchise, just look at ASOIAF at HBO and LOTR at Amazon!
Sheridan, on the other hand can launch his passion project, Empire of the Summer Moon, at NBC Universal. I believe it will be way bigger than Yellowstone. He is also getting a huge pay raise, which he deserves after all his struggles on the fringes of the industry