If you time, please file a bug report on Mozilla’s webcompat.com with the steps you took and a screenshot. Mozilla’s webcompat developers will try to debug the website, reach out to the website’s web developers with a proposed fix, and until the website is fixed, add a site-specific intervention or UA override in Firefox itself, if possible.

Looks like there are already a couple bug reports about whatsapp.com, but not the forever-refreshing page you see:

https://webcompat.com/issues?page=1&per_page=50&state=open&s...

I don't think I can be of much help but WhatsApp web has been working for me on Ubuntu with all Firefox versions since WhatsApp web has been a thing. Did you try to start Firefox in safe mode, no addons and/or a fresh profile?

If anyone finds a solution it would be greatly appreciated. I have been cut off from a huge number of sites due to infinitely refreshing cloudflare.

It's absurd that this is even possible. They should at least provide troubleshooting advice for end users.