xiota [1] filed a deletion request for firefox-hg [2]: This package has been failing to build for a few months because the mozilla-unified repo cannot be cloned. Switching to the mozilla- central repo would make it too similar to aur/firefox-nightly. Comaintainers have discussed the issue and generally agree this package may be retired.
[1] https://aur.archlinux.org/account/xiota/ [2] https://aur.archlinux.org/pkgbase/firefox-hg/
