MarsSeed [1] filed a deletion request for ubo-extra-git [2]:

Source GitHub repository last updated in 2020, and it is archived (made read-only), so the project is deprecated.

Not exactly sure what was the "extra" companion part to uBlock Origin the browser addon. The latter is still alive and kicking. :)

I propose to delete this VCS package for the discontinued "extras". Safe to drop; nothin depends on it.

[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/ubo-extra-git/

Like it says in the README the threat model of this extension doesn't really exist anymore, since the main company doing it was bought by Akamai. The extra part was blocking ads and scripts that were disguising themselves as first-party, which wasn't as simple for chromium-based browsers compared to firefox. Also note that this was an official extension to uBlock Origin +1 to the deletion request