I wanted to add my domain to Quic.cloud to use its CDN. But they need me to add their nameservers instead of my registrar’s (which is Cloudflare in this case).
If you’re glued to Quic.cloud for some reason (eg out-of-the-box optimization for WordPress + Litespeed webserver), it’s better to disable Cloudflare’s proxy than layer the two services together.
You do this by pointing DNS-only records to Quic.cloud.
And if you prefer to manage your DNS records yourself from your Cloudflare dashboard, here’s Quic.cloud’s manual Cloudflare integration guide: https://docs.quic.cloud/onboarding/cloudflare/
Note that this turns Cloudflare into a mere DNS resolver for your domain, and you’ll need to handle ALL security and optimization at Quic.cloud's end (to the extend of their platform’s capabilities).