gremlins/readline 8 - SOLVED mirror delay
Either the pkg is broken or it is supposed to come with something else that hasn't synced yet.
gremlins/readline 7.0.005-1 8.0.0-1 0.03 MiB
Ignore it if you haven't tried the update.
If you have already, use an other artix installation or live, and link the library
# ln -s /mnt/usr/lib/libreadline.so.7.0 /usr/lib/libreadline.so.7
# pacman -S system/readline
EDIT: See below