…And now I am using an Ubuntu keyserver.
Ah. Small hickup: Due to naming conventions many default programs in the meta package does only have adawaita icons. Not a big deal, but I think it has to do with a name change: all the 4.15 packages are called org.xfce4.filename while the old ones were just xfce4.filename. Question is if that’s a name change standard or if it’s because it’s the dev packages.
I’m not sure it’s Adwaita icons, I think it’s the defaults, e.g. the packaged
Possibly there’s a move towards an icon naming standard, or upstream have just changed the filename.
I think you are right about the first part. About the second it sounds like a new naming standard. Well, we’ll see.