After a few seconds of surpassing the highscore, the client starts sending ss 14 1 every frame despite the switch not changing at all. After enough time has passed, the server cannot keep up with reading packets from the client and drops the client.
The issue is with GMI().SwitchSet() unconditionally sending a packet every time the game forces an update. However it is not clear yet if this is a correct fix and will not produce side effects.