alt Hacker NewsComments below is from the perspective of an arch Linux user, not maintainer or authors of some software.
When installing softwares on arch Linux, first searching for official packages provided by Arch Linux maintainers, then official installation methods approved by authors of the software, or AURs which do the installation in the exact way as the authors of the software describe.
A search on the default installation method of Firefox and librewolf package on arch Linux is listed below.
If AUR is required to install a package, note that AURs are not trusted by default because not all AURs are not maintained by trusted users. Always check the source file and the installation method documented in PKGBUILD. Don't do the installation until EVERY line in the PKGBUILD is reasonable.