When you trigger a deploy from CI via either a deploy hook or the API the trigger returns immediately. Which also means it does not communicate whether the deploy succeeded.
The screenshot below shows a CI process in which both deploys to render actually failed to deploy.
However since the actual deploy command doesn't persist through the deploy or return that information then you have to poll Render to find out whether it's succeeded.
Doing so is a non-trivial operation. This is a public script that does so:
However well intentioned they are, I don't use any uncertified scritps in CI processes becuase of the tremendous security risk and so it would would be excellent for Render to either:
  1. Offer their own, certified Github actions script to make it easy to poll for success
or (better still)
  1. Offer a way to make a synchronous call to Render which fails if the deploy fails
Update
___
I've now written the github script to do this and have shared it below. It's a bit of a waste for all of yoru customers to be battling through this though :/