"No shady privacy policies or back doors for advertisers" proclaims the Firefox homepage, but that's no longer true in Firefox 128.
Less than a month after acquiring the AdTech company Anonym, Mozilla has added special software co-authored by Meta and built for the advertising industry directly to the latest release
What about ungoogled-chromium?
I used to run that years ago and what I remembered was that it was a handful to maintain with updates when I used to run it on windows. It could be completely different now, so don’t let my past experience hold you back from trying it out.