Why not take a screenshot of the CF error and send it to the website owner? It would freak me out if I thought a significant number of my website's users were being blocked by CF.
+1 to anybody who creates a site to name and shame CF customers who block legitimate traffic. For a few months now I've been taking screenshots every time this happens, but with no end goal. Complaining to the individual site owners feels like a lifetime commitment, and there are virtually none I need that badly.
I have done that numerous times. Even sent a screen recording of the Cloudflare spinner of hell. The response is always the same: you must be running some shady software on your machine.
Cloudflare is acting as judge and executioner, and site owners never accept that the product may be faulty.
How do you send them that when you can't access the contact form and/or contact information on their site because Cloudflare blocks it? (assuming a normal visitor, not someone who knows about whois etc.)