(In reply to John Bieling (:TbSync) from comment #1)
I cannot confirm this for "standard" usage in 102 and 106 (using the proposed FileLink provider for Send).
Hmm, I am not sure how this could not be a regression, as it is a difference in behavior between Thunderbird 91 and 102. It is also a difference in TB 102 between using the keyboard and context menu.
However, there is a special case: When the uploaded file (to be exact: its link) has been used already in a sent message (or the message has been saved as a draft), then it will not be deleted from the server if it is removed from the message, as that would invalidate the link in the already send/saved message.
My "FileLink provider for Send" add-on sets the
reuse_uploads Manifest property to
false, so uploads should never be reused in any case. The issue is that when the attachment is deleted (using the keyboard) and the links are removed from the message,
cloudFile.onFileDeleted event never fires, so the file is not actually deleted from the server as the user expects.