Latest version of Thunderbird downloads deleted messaged from gmail, 2nd request.

                                         NOTE:  I changed no settings at either end.

Since a recent TB update in August, the program now downloads previously-deleted messages from Gmail. TB downloads from the In folder (OKI), but also current messages that I sent to Trash folder (not OK). Example: 50 new messages appear in the Gmail In folder. I delete 30 messages from the In folder, and they correctly move to the Trash folder, leaving 20 in the In folder. I next launch TB on my Win10 PC and press F5 to begin the download. Until recently, I would get the remaining 20 messages and ONLY the 20. Now, TB downloads all 50, as if 30 were never deleted. NOTE: I changed no settings at either end. If I go into the Trash folder before downloading and delete today's trash, those messages are totally gone and won't download. But this was never necessary a few weeks ago. If any reader had and fixed this annoying problem, please tell me how you did it.