You should get a certificate warning, and if you choose to proceed anyway, you'll get a Cloudflare-originated 403 Forbidden page.

Now set 8.8.8.8 as your DNS and reload the page, and you'll see it open normally. No broken cert, no 403 status code, just a working website.

I found this very unexpected. Am I missing something obvious, or am I not the only one surprised to see this?