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.
That’s what SponsorBlock already does. It however doesn’t detect the sponsor but instead it jumps over a part of the video marked with timestamp but with different people seeing different lenght ads, these timestamps no-longer match.