YouTube Subscription Updates

For the last 3 or 4 days,I've been getting the blue dot that indicates new material on a subscribed channel.

It has done this on nearly all of the 400 subscriptions I have.

Almost none of the channels have had any new material.

In fact,most all have no new material for up to 8 years.

It seems like it's just going thru my entire list of subscriptions,and telling me that they have updates.

It keeps doing the same ones(actually all) over and over and within minutes.

What's going on ?