sudo pacman -Rns manjaro-browser-settings
If you dont like/want it … then remove that package.
It does nothing else but set homepage and bookmarks on multiple browsers.
Oh addendum. It also sets some variables like these too:
about=Mozilla Firefox for Manjaro Linux
app.distributor=archlinux
app.distributor.channel=firefox
app.partner.archlinux=archlinux
None of which is necessary.