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 wonder how that will interoperate with timestamps provided by users in comments or by the video creator themselves. Maybe those can be used to detect inserted ads.
I have actually been seeing some timestamps that are completely wrong lately, maybe this is why.