What happens if I shut off my Switch while visiting another island?

There are so many cut/loading screens when visiting another island (with people coming and going), it seems more efficient to just turn off the Switch, but what does that do to the visited town and my own save state? Does the owner of the other island just see me leave normally? Do I keep everything from my last save, or does it revert to a state before I visited the island?

Solution 1:

Your state isn't saved. You lose everything you got in that island. The owner doesn't see you leave normally, you just dissapear.

Solution 2:

You definitely keep items that are recorded as part of your "player save", and you lose anything kept in the "world save". The inverse occurs when the island owner is who disconnects. You have just come across the method many players use for item duplication.

After 60 seconds, it will also make an announcement to everybody else on that island:

PLAYERNAME has quietly left...

This is the same thing happens if a player's internet drops out while they are visiting a friend.