When playing offline as a secondary player in a split screen format your skin, last location, and any items you had on you will be forgotten should you exit the game and come back later.  However, logging out and back in will sometimes bring some of these back but not always.

The same goes for playing online in realms.  Although it is mostly the skin that is forgotten in this instance.

This issue has been occurring since at least 2017, as indicated here: https://bugs.mojang.com/browse/MCPE-26498