If your hosts have 172.16.0.0/8 set up as the local network instead of the proper 172.16.0.0/12 range, they will not be able to reach IP addresses on the internet which are part of the /8 subnet, but are outside of the 172.16.0.0/12 range. The IP address from Cloudflare (172.65.32.248) is such an IP address: it's NOT one of the private IP ranges of the 172.16.0.0/12 subnet, but it does fall within 172.16.0.0/8. So if you have 172.16.0.0/8 set up, your host is trying to reach Cloudflare on your local network, which of course isn't going to work.
If you search this Community for 172.16.0.0 you should be able to find a few threads with the above issue.
Edit: I should say 172.0.0.0/8 by the way as that's the proper CIDR notation.