So I have a subdomain added in the DNS of Cloudflare that I have pointing to my webserver. If I enable proxy, it will then take me to a Shopify` error page 503. But If I turn off the proxy, then the site works like normal.
I have no idea what I did wrong, but any suggestions would be greatly appreciated. As a last resort, I’ve cleared the cache, deleted and re added the DNS record.
You did nothing wrong. Your domain was probably with Shopify at one point.They don’t have the greatest track record for removing domains from their Cloudflare for SaaS account when their customers move to another provider. You can Liberate The Hostname yourself.