There was. Some channels even saw most of their decline from mobile/TV viewers.

That doesn’t necessarily mean that wasn’t also related to the adblocker issue, though. How the algorithm reacted to the dramatic change in views could have made waves that saw channels de-recommended or caused it to ignore sections of a viewer’s watch history and thus the recommendations shown to them as well.

With the algorithm everything gets tied together so much that any disruption can have unpredictable effects.