The GameXplain YouTube channel has confirmed that Kirby Star Allies seems to run at a locked framerate of 30fps.

Although the game’s title screen and pause menu seem to run at 60fps, the gameplay and cutscenes run at a solid 30. If we had to speculate, we’d guess this is done to avoid any dips in framerate when things get crazy. We’re not too heartbroken, especially if the 30fps is rock solid.