Ask HN: Are github.com previews broken on Slack?

Have any Slack users noticed that github.com links no longer unfurl? Previews for github links are usually pretty useful since they show repo information, comments, pull request descriptions, etc. This is the case on all Slack servers that I'm on.

Yes, I've checked `/admin/attachments` on multiple servers, and github.com isn't in the don't-show-previews list.

Slack allegedly has a 32KB fetch cutoff which has caused problems before (https://blog.daveallie.com/slack-link-unfurling/), but the og:image tag seems to be well within the first 32KB of the response.