Have you been served an unexpected Cloudflare captcha on Firefox?

I've been trying out Firefox again on my new install. I saw a Cloudflare 'browser check' pop up for a handful of random websites, which blocked me for a second or two before redirecting, and didn't think anything of it. But just now, I was logged in to a popular coding website clicking an internal link, and Cloudflare served me a captcha challenge.

There's nothing novel at all about my setup. I'm on macOS, home internet, I don't run any servers, only extension installed is ublock origin. Have never once seen these screens before starting to use Firefox again in the past few weeks, so I can only guess that's the only variable here. Thus, reaching out to see if this might be a shared experience.