Pretty rich from a compile-from-source distribution
A dumb-as-rocks tinderbox can do the task of "build the thing in all valid configurations". Good luck getting the hardware needed to do all that testing in a timely manner on an -IIRC- 15K USD budget, or finding people to volunteer it in this economy. And good fucking luck getting LLMs to do the diagnostics, writeups, and -most importantly- shepherding required to get the bugs your testing reveals actually fixed in upstream.
Upstream not giving much of a fuck about whether anything other than Google® Chrome™ can be produced from Chromium is a big part of the reason it's being dropped from Gentoo. And yes, I 110% agree that Google is totally entitled to give zero fucks about non-Google users of Chromium. Gentoo is equally entitled to stop packaging Chromium.
For just one of many examples, see [1] where the Gentoo developer had to submit a patch upstream for a Chromium build toolchain bug that to 99% of experienced Linux users is bordering on unintelligible due to how much specific knowledge is needed to understand the bug.
Problem is solved!