I realise there are potential ramifications to this but my concern is regarding SEO and duplicate content. If my app’s app.onrender.com address ever gets crawled then my app is now available on two hosts.
Is there anything currently in place which mitigates this issue?
Adding on to what @marc said, regardless of which language or framework you’re using, you should be able to add a rel=“canonical” link tag to your HTML to indicate that only the pages served at your custom domain should be indexed by search engines. Feel free to follow up with any questions about this approach!