The breadth of responses here about people who can't reproduce this (or can) is one of the most frustrating things about working on fingerprinting protection. I also cannot reproduce this behavior, and have to assume that there is some complicated, behind-the-scenes risk assessment that is being done and some people trigger it and some don't. If any Cloudflare devs want to chat, I would love to. While not a normal way to contact us (support requests will be ignored), I can be reached at security@mozilla.com