[alt text: two frames from Spongebob, edited into a meme with extra images and text. The first frame shows Mr. Krabs, labeled "Sony", who is surrounded by different Playstation games, including The Last of Us, Spider-Man, God of War, and Ghost of Tsushima. Mr. Krabs is saying, "All of you, off to PC!". In the second frame, all of the games have left, except for Bloodborne. Mr. Krabs/"Sony" is pointing at Bloodborne and saying, "Except you, stay."]
It's the only explanation. Sony are sitting on the IP to sell as an exclusive later down the line. It would be financially stupid of them to release a 60fps patch, even paid, for the PS5 at this point.