A screenshot shows an "Error 451" page, but how can that even happen? It's https. Unless Cloudflare is also the web host, they can't change a page like that without the client seeing a certificate error.
If they can serve your site with https normally, they can serve any content they want under it.
In some other cases I suppose they could downgrade the connection to HTTP in order to show their 451 page, but if the domain is HSTS'ed then that wouldn't work either. That'd have to just black-hole the query like Google does.
Non-authoritative answer:
ivesoccer.sx nameserver = lou.ns.cloudflare.com
ivesoccer.sx nameserver = venus.ns.cloudflare.com"Cloudflare Reverse Proxies Are Dumping Uninitialized Memory" - https://news.ycombinator.com/item?id=13718752