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.
Even when you don’t know the language, you can judge if something is an ad just by an overly excited tone of voice. I wonder if someone has tried writing an ad detection algorithm already. It would still be a lot heavier on resources than SponsorBlock.