I’ve never had issues with Cura losing my stuff (been using it with an Ender 3 since… 2019 I think) but the backup plugin is connected with your account. It’s a wonderful thing! New computer? Login, restore backup, everything is like you left it.
I do make sure to use it before any update because I have seen the same kind of posts as you have.
My understanding (potentially obsolete!) is that the integrated gpu of the Deck isn’t supported by, uh… whatever the AMD equivalent of Cuda was called, also there’s a chance you’d have to install it manually too.