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 and then re-add the custom domain back to your project.
- This does mean that you will have to contact us if you want a custom domain removed. Click here to go to the support form where you can request domain removal. When filling out your support request, please use the email that is connected to your Glitch account. In the message, let us know the custom domain(s) that you need removed.
You should receive a response within 24 business hours if not sooner.