Moving towards the Chrome-Standard

Every day I read something that makes me feel a little more like I'm living in a cyberpunk dystopia. Today it's the fact that Chromium is so dominant that a large number of website developers seem to ditch testing in non-Chromium browsers. This is evidenced by non-Chromium browsers, like Firefox, loading some sites differently, e.g., by pretending to be Chromium, because the website developers wrote sloppy code that only works in Chromium. So I guess, especially with the announced anti-adblock in the next Chromium iteration, the choice is to use a low performance browser that is actively hurting your privacy, or experience friction, knowing that Mozilla can't find and carpet over all the bugs in other people's code. For me, the answer remains Firefox and it's forks. However, for many, I fear this will ingrain Chromium dominance deeper and deeper. Please: how is this market dominance, evidence by soft-forced hot fixes only in non-Chromium browsers, not anti-trust?