Not sure if this is the same issue, but I receive something similar on a daily basis with all 115 versions (current is 115.7.0 snap) One message received is shown as 2 threaded messages. Some emails were deleted some time ago. Only one instance of Thunderbird is running. Example: https://bug1848738.bmoattachments.org/attachment.cgi?id=9376977 (sorry, cannot understand how to put it inline here)
Bug 1848738 Comment 15 Edit History
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Not sure if this is the same issue, but I receive something similar on a daily basis with all 115 versions (current is 115.7.0 snap) One message received is shown as 2 threaded messages. Some emails were deleted some time ago. Only one instance of Thunderbird is running. Example: attachment 9376977 [details] from bug 1848738