I don't think images from GitHub can be embedded into a Trac ticket, because of cross-origin restrictions. The images in the ticket description aren't visible. See screenshot attached below. When you have a chance, would you mind re-embedding the images from another source (and with http, not https) or upload them to the ticket as attachments?
On the other hand, I'm not sure why this ticket is on Trac. Shouldn't this issue be addressed in Gutenberg, on the linked issue https://github.com/WordPress/gutenberg/issues/11436 ?