YouTube is currently experimenting with server-side ad injection. This means that the ad is being added directly into the video stream.
This breaks sponsorblock since now all timestamps are offset by the ad times.
For now, I set up the server to detect when someone is submitting from a browser with this happening and rejecting the submission to prevent the database from getting filled with incorrect submissions.
I really like the idea of Nebula, but the way they market themselves as “creator owned” without being an actual workers cooperative seems deceitful (still much better than YouTube, though!)