Benefits:
* Security [1]
* SEO [2]
----
[1] When using a custom domain one of the benefits is that instead of having the DNS pointing to Render, you can point it to Cloudflare (for example) as a proxy.
This reduces load on the origin server and the {project}.onrender.com seems like a bit of a loose-end.
Could somebody DDoS this server, bypassing cloudflare's protection?
[2] Add
x-robots-tag: noindex
header to deploys without assigned custom domains. This would allow testing one's full Web site content on Render without needing to alter a repo's existing "robots.txt" file yet avoid risking the duplicate-content penalty from Google and other search vendors. Similar functionality is provided by Vercel (https://vercel.com/docs/v2/edge-network/headers?query=robot#inlinecode).