One issue is that would be nice someday for some Manjaro app to notify a user after an upgrade that new wallpapers are installed, but to not just switch their wallpaper to one of the new ones automatically without even asking them. I was just upgraded to GNOME 42 and my wallpaper changed without me doing anything, which didn’t seem very nice to me.
A related issue would be to preserve the previous wallpapers, not remove them, say if a major GNOME upgrade gets rid of previous wallpapers.
A last issue would be packaging old wallpapers from GNOME, KDE, et al., as for instance, bundles associated with a given version of a desktop environment or Manjaro itself. Maybe this might overlap the last item. Maybe in advance of an upgrade the user is notified that new wallpapers are coming, the old wallpapers will now be available in package xyz in the community repo for posterity, and maybe there would be some UI widget prompting the user to decide if (in advance), they want to keep their existing wallpaper unchange, and just simply informing them that this will install a new legacy wallpapers bundle package.
I had a specific wallpaper set by choice before the upgrade. After the upgrade I had a different wallpaper. I did not change it. The upgrade changed it. I’m pretty sure it was a Manjaro wallpaper too, not a GNOME wallpaper, that I had set before the upgrade. This was my main issue in this post. Are you saying the GNOME package will just overrided my own settings?
Moreover, I was not able to find, as an example, the “Icetwigs” wallpaper from GNOME 3.38 in the AUR, after losing it during a previous Manjaro upgrade.
You mean this wallpaper? It was part of gnome-background package. Only Gnome developers decide what wallpapers will be added or removed in this package. You always can explore repository and find your favourite wallpapers.