Discourse should still generate valid HTML to display the image. Imgur throws a 429 error when the Discourse server tries to pull a preview of the image link, but Discourse treats it as if it were a 404 error. On my forum this image is not displayed with just the URL:
https://i.imgur.com/eHltaVt.jpeg
But the following HTML works to display the image:
<img src="https://i.imgur.com/eHltaVt.jpeg">
That is what Discourse should generate for the baked post even if it receives a 429 when the server hits the URL, and it should only leave the naked URL if it gets a 404 error.