Comment by harshreality

The only symptom is that captcha never completes.

I have more restrictive protections on. If you use just loose settings, it completes, but advanced fingerprint protection, for example, breaks captcha completion.

This is very known issue.

https://news.ycombinator.com/item?id=35742606

This matches my experience as well. As a FF user, I very occasionally encounter problems, but these don't seem to be correlated to their using CF protections. Much more often I find sites broken that rely on cloud domains with bad reputations, which my DNS filters block.

I was actually wondering if the stuff that Mozilla's talking about here will be used by bad bot people to try to circumvent CF's abuse protections. As I recall from when I was working with them, CF's service relies in part on being able to identify botnet attacks by doing its own fingerprinting.