The custom domain that I set up with Cloudflare now says 'Not Found'. What's going on?

Currently, there is an issue between Cloudflare proxies and fly.io that causes this.

Here is how to fix it:

• Remove the proxy.
• Remove the custom domain from your project. 
• Then, re-add the custom domain back to your project. Note: as our custom domain feature is temporarily unavailable, if you remove any of your custom domains, you will not be able to add it back