Waterfox looks worth a try, but I opted for LibreWolf because it's verified on Flathub and Waterfox is not. It looks like the Flathub version of Waterfox was packaged the same BrowserWorks Ltd that makes Waterfox, but they didn't take the extra steps to get verified so we can't be sure. Hopefully they can remedy that. Browsers are too important to install from untrusted sources.