I recently configured my discourse installs to use a CDN and store uploads and site assets in S3 compatible service. So far everything else has worked, but our custom emoji images fail to load.
When looking at the html I noticed that the URL for one of the emoji is //thrivecommunityforum.s3.eu-central-1.wasabisys.com/original/2X/6/6b7f95a2cfc7810d26c7e170ebf926ba8634261b.png
(this doesn’t load because I set an override to prevent public access to the bucket after seeing in the file manager a warning that public write was enabled for the files)
Whereas all the other uploaded images and site assets correctly reference the CDN I configured: https://thrivecommunity-uploads.b-cdn.net/original/2X/6/62f6697da0e3cd71a7d4f1eed518641f8428150b.jpeg
In-built emoji URLs look like this: https://thrivecommunity-cdn.b-cdn.net/images/emoji/twitter/thinking.png?v=9
So my conclusion is that there might be a bug in the custom emoji handling when generating the image links, which skips out on using the CDN that is configured to be in front of the S3 stored files.
I tried to find relevant topics, but I just found this: Custom Emoji does not use Amazon S3 which seems outdated as discourse is attempting to use S3 to serve custom emoji on my site.