We simply sent our nameservers to Cloudflare and setup * to point to our server. I had a cname for www which directed to * by default. It’s been working for over two years with no issues. No redirect, no page rules of any kind. I just now cleared the cache. Just all of the sudden Cloudflare is redirecting to that strange site.
I’ve since set my DNS to proxy and upgraded to pro. It’s a pretty vanilla site, rules. The only thing we did that was kinda recent (6 months ago) is installed win-acme to create Let’s Encrypt SSL certs for the site.