kageurufu [1] filed a deletion request for plv8-9.4-bin [2]:

obsoleted by plv8-bin

This package was foolishly named -9.4-bin, for postgresql==9.4. As postgresql has updated, this package is no longer required

[1] https://aur.archlinux.org/account/kageurufu/ [2] https://aur.archlinux.org/pkgbase/plv8-9.4-bin/