Did anyone beat Batman Arkam Night on SteamDeck? Is It totally playable?

Hi, i just bought this game because It was verified and on sale, but i noticed It tends to go from 40fps to 28fps sometimes and looking online It seems like the last 20% of the game adds particles/effect that lowers even more the performance.

So without lying, can anybody who played the entire game on SteamDeck tell me if it's true that progressing will give me this problem or any other?

I'm asking this because i could try to get a refund (even if the price was low) mostly because i wont really play a game that goes constantly under 30fps, and It occupies 50GB of space which Is pretty big for a game i wont play a lot.