【Nintendo Switch 2/Puyo Puyo Tetris 2S】Are there any differences in gameplay behavior between “Game Share” and “Multiplayer” modes?

Yes, there are some differences. In Game Share, only Player 1 (the host), who owns the game, can use features like vibration and mouse controls.
Guest players do not have access to these features. Additionally, there may be differences in visual quality and frame rate on the guest side.