I tried to add source link https://pagedout.institute/
to wallpaper on the page Upload, but I got an error:
Error
Invalid URL. Please include the full link (https://...)
But... I was able to add it without error on the final page e.g.https://wallhaven.cc/w/9drjlw
!
I don't understand why there is such a difference and errors when adding it and I think it's a bug on page "Upload".