It looks like it has been temporarily dropped for some reason.
Yes, compiling a browser is insane unless you need to modify the source code or something. But there is a binary available you can install instead.
❯ paru -Ss ungoogled-chromium-bin
aur/ungoogled-chromium-bin 130.0.6723.58-1 [+88 ~4.16]
A lightweight approach to removing Google web service dependency
That one is pre-compiled and should have a considerably more modest build time.