you shouldn’t run software that accesses such intricate personal information if you don’t trust it, if it can be updated to change to grab all that data.

Yes, and you should also brush and floss your teeth, do physical activities, buy local produces, recycle everything, do your due diligence on all political candidates, etc, etc. In practice we ALL have to make pragmatic choices. There are not a lot of browsers and basically for fully featured engines there are (arguably) only 2, Chromium by Google and Firefox by Mozilla. One is an advertising for profit company, the other is not. If you genuinely care a lot about privacy though you might not have to use either, you might be perfectly fine with much simpler browsers like Links or even lynx and I can tell you with a lot greater confidence that there no data will leak. You can also containerize your browser using e.g. https://docs.linuxserver.io/images/docker-webtop/ and then run within there whatever you want.

since Mozilla seems to potentially give itself a license to all your data, apparently.

That's not correct, you mean some data from your browser usage. I think it's important to be precise here otherwise through shortcuts you try to convince yourself, and others, about a problematic situation that just does not exist.

So which browser do YOU trust and why?