Changing iOS 18 iPad wallpaper

Yesterday I updated my iPad to iOS 18 and since then the entire wallpaper system doesn't work. When I long press on the lock screen the wallpaper turns black for a second but then the wallpaper editing menu thing doesn't appear. Same when I go to wallpaper in my settings, it just shows me the gray rectangles with the blue plus thing in the middle but nit even my current wallpaper set. If I try to tap on that blue plus the time and date, the battery and the home button line thing (I hope you know what I mean) turn darker and then the iPad freezes for two seconds.

Please help I desperately want to change my wallpaper to a cute fall theme :)

[Re-Titled by Moderator]