The project is dead, and plocate is the perfect replacement

https://wiki.archlinux.org/title/Locate

The project had a last commit in 2017, mlocate was removed even from Ubuntu at this point.

To add to this, the constraints on the systemd service make it so that the updatedb.service produces a much more limited file than running updatedb would, making it nearly useless.

[0] # systemctl start updatedb.service

[0] # ls -lah /var/lib/mlocate/mlocate.db
.rw-r----- root locate 553 KB Wed Aug 21 19:33:09 2024  /var/lib/mlocate/mlocate.db

[0] # updatedb

[0] # ls -lah /var/lib/mlocate/mlocate.db
.rw-r----- root locate 2.4 MB Wed Aug 21 19:43:44 2024  /var/lib/mlocate/mlocate.db

plocate, which Arch already ships is a faster, more storage-efficient, still-maintained replacement, with working systemd units - https://plocate.sesse.net/

[0] # updatedb 

[0] # ls -lah /var/lib/plocate/plocate.db 
.rw-r----- root locate 2.2 MB Wed Aug 21 19:45:30 2024  /var/lib/plocate/plocate.db

I would suggest to just drop mlocate from the repos and from the wiki.