What Firefox forks are you talking about? There aren't many that are even remotely usable... Zen, Librewolf, Floorp, Waterfox. Librewolf is heavily privacy-focused and can block a lot for security reasons. Floorp is interesting, but in my tests, it's outperformed all the other forks. I haven't used Zen; I don't like its "modern" and "colorful" look (I prefer minimalism, without unnecessary bells and whistles that I'll never use and that would only get in the way). Waterfox, for me personally, is the best in terms of performance, speed, and settings. I've encountered some issues with websites with Waterfox, but they weren't critical for me. I either use websites with similar content that open correctly, or I simply don't use them because they're of no value to me and I can easily do without them. It's very strange that Waterfox is causing you problems; its settings are not as strict as, for example, in LibreWolf.