Thunderbird Email Count

Since the last three Thunderbird upgrades, incoming mail counts are severely wrong. When getting messages, it may report that Thunderbird is downloading 26 new emails. The actual count could be way less, close, or right on the money. It never downloads more than it says, only less.

The behavior is not a deal breaker, just wondering what may cause this.

I do have a junk folder and emails that land here are in the count.

Just weird.