OS: Fedora 40 KDE.
When executing the appimage in Terminal, it gives this error
$ ./XnView_MP_194.AppImage
/tmp/.mount_XnViewOgfEAg/usr/XnView/XnView: error while loading shared libraries: libnsl.so.1: cannot open shared object file: No such file or directory
[edit] (solution)
The tgz download works fine. This is also the solution when running Fedora Linux.
Download links in this thread: <LINK>.