Thank you very much @chrisrg @smu44 and @Manoj.
One more practical question. I now have a 1080x1920 wallpaper on a 1080x2160 display size.
What would be the most recommendable way to deal with this? Letting the system stretch the unedited wallpaper to fit my screen OR picture-edit the file (btw, there’s also a 1440x2560 version in the Commit) manually to fit my screen?