It isn't being taken away. You can still play it, just not buy it. You'd have to buy it again anyway even if you owned the original release on PS5. They aren't allowed to update the old version from my understanding. It's basically a new game. If they are struggling to get it to run on a PS5 it isn't gonna run on a PS4.
It's a not great situation but at the end of the day you should be mad at TellTale for being a terribly ran company, not at TFP for bringing the game back to consoles.