POSSIBLE FIX:
I think changing your default DNS servers to Google 8.8.8.8 or Cloudflare 1.1.1.1 might bypass the spanish sunday ban on Cloudlflare.
macOS + Cloudlfare 1.1.1.1 https://developers.cloudflare.com/1.1.1.1/setup/macos/
Google 8.8.8.8 https://developers.google.com/speed/public-dns/docs/using
Nope, it’s IP ban. At least for Vodafone and Telefónica.
I don’t think it’s a DNS ban, it looks like they actually ban connections to the IP range.
But you can just use a VPN.