Super Backgrounds were some of the highlights on MIUI, anyway, on HyperOS my favourite "Mars" is broken. I restarts several times then falls back to "Moon". "Saturn" works as well, but "Mars" is broken somehow.
Since you are still on OS1 and A14, you can try do deinstall the super wallpaper app for Mars and reinstall the app version from December 2023. You can download it from apkmirror. I did it by myself and it worked.
On OS2 and A15 it is additionally required to use the Google wallpaper app.
Ok, didn't know it's a separate app and able to be deinstalled, I thought it's part of the ROM.
If found it in the apps list, it's installed as Version ALPHA-2.7.565-09261422-vulkan. https://www.apkmirror.com/apk/linuxct/mars-super-wallpapers-default-linuxcts-port/ only has linuxct-2.6.260-08131855-211107 from 2021.
For now I got it working again by clearing the data and cache of that app.
Ok thanks, my fault.Looking in Settings->Apps->Manage Apps-> search for "Mars" I see all 4 SuperWallpapers named "*Mars".. just the icon differs.
So I have the recent version already. As it was fixed by clearing data, I don't re-install something from apkmirror.
System language German?
Change to English, choose super wallpaper, switch back to German. Now it should work.
German language repository has been updated in the meantime. Maybe with next ROM super wallpaper will work again without any issues.
The super wallpapers are bugged in the latest versions even for stock rom (except moon), we have to wait for Xiaomi to fix it, In the meantime, you can uninstall the buggy version and install an older version that works.