Steam Deck FPS Limiter Not working

As the title suggests my FPS limited via mangohud (I think thats what its called) is not working. I can go from 60 down to 10 fps and the screen blips out like its changing but the in game fps is still the same and pushing beyond the limit. Dont know if this is a bug or something is missing. Using Steam Deck LCD model. Any help would be appreciated as not every game has an in game limiter.