Inline image from email disappeared when becoming a GitHub comment

Randomly on a whim I had decided to try replying to a GitHub email instead of commenting the normal way, and the email I had sent contained an inline image.

It seems like this inline image just vanished at some point between leaving my mail client and arriving in a comment box.

The comment in question was this one. It has been edited since, as I tried to manually fix the image in it, and it turned out that didn’t work either.