A weird bug with Monster Hunter Rise I ran into while playing docked, is that the game has issues when two controllers are connected (ie Deck built in controls and an external controller). It might also mess up if you have only one connected, but it’s designated as controller “2” or something like that. Iirc the game would play fine, but everytime a monster roared it would drop to 0 fps for several minutes, seemingly frozen (but Deck UI would work fine).

There might be multiple solutions for it, but I think what I did was used a decky plugin to disable the deck controls, and then made sure my wireless controller was set to be controller 1.