During this incident, all video posts to bluesky failed to send due to a change on the bluesky API. The format used on our API for sending a specific parameter was now being rejected by the new validation on the bluesky API, resulting in HTTP 400 errors. For Image and text posts, these use a different code path and were unaffected. This resulted in around ~1350 failed video posts for a reported 1300 users.

While this is a third-party change, we previously had a similar issue due this same formatting of data, so we are proactively analysing the rest of our codebase to find any other instances that could cause related issues in future.