Genshin Impact naturally runs terribly for PlayStation 4s, but so do a majority of games from 2019-present without extreme optimisation, or exclusivity. Ghost of Tsushima for example is a 2020 game and runs fine on base PS4 because it’s optimised as an exclusive title, but the console sounds like a jet turbine.
I have a base PS4 and played Genshin Impact there for half a week before moving to mobile-PC. The loading times on PS4 are much longer than they are on the other platforms, and the frame rates were constantly low. Even my previous phone, iPhone 8, that still ran the game badly but did manage, had better loading times than my PS4. I would assume the PS4 Slim, because its hardware is cheaper to make it more affordable, would be even worse in that regard.
I don’t know if Xbox has the same issues or not. I haven’t seen any complaints about it… now that I mention it I’ve never seen discussions about the game on Xbox but I’m certain it’s there, and cross play compatible with PC and Mobile.