@iolaire yes, it's a bit unfortunate. I try to not "challenge" dial-up/residential/cell but some combinations (outdated browser etc.) might trigger a challenge.

Cloudflare provides a "challenge solve rate" (CSR) and it's a little bit high today for me — 1.2% of presently 751 challenged requests were solved. Eight slightly inconvenienced visitors is better than getting scraped to death, with resource warnings from my hosting company, etc.