game data lost after app switch

pecans23  Your saves and other user data have nothing to do with what game launcher you use, or with the game's program files at all under normal circumstances.  All user data is stored in Documents > Electronic Arts > The Sims 4, and unless you've installed the game there too (which is problematic for multiple reasons), neither should affect the other.

If you have installed Sims 4 anywhere in Documents, please uninstall it and reinstall it elsewhere, before doing anything else.  If you've created a new save you don't want to lose, grab it out of the saves folder first because uninstalling will remove everything in the "The Sims 4" folder that contains the game's program files, regardless of whether there's anything else stored in that folder.

For further help with disappeared user files, please see the first post of this thread:

https://answers.ea.com/t5/PC/CURRENT-ISSUE-Sims-4-saves-user-content-disappearing-PC/td-p/12475370