polyzen [1] filed a deletion request for firefox-refcontrol [2]:
Doesn't have multiprocess shims -- not sure if this is still installable. Hasn't been developed in years.
WebExtension alternate: https://aur.archlinux.org/packages/firefox-referer-control/
[1] https://aur.archlinux.org/account/polyzen/ [2] https://aur.archlinux.org/pkgbase/firefox-refcontrol/
Request #8396 has been accepted by Muflone [1].
aur-requests@lists.archlinux.org