If a feed has 100 consecutive read errors, we unsub from the feed.
However, there is a mistake in the way it's implemented, and it would unsub after the 100th error.
So if you subscribe to a feed for a long time, and it occasionally has an error, say once a day, after 100 of them (or 100 days) we'll unsub from the feed.
possibly the source of the problem we've been tracking down.
Before fixing the bug, I'm going to run a utility script that tells me which feeds have ctConsecutiveReadErrors > 0 and what the numbers are.
Are you sitting down? There were 631 of them. Some of them had as many as 91 errors.