Thunderbird 102.8 when I open an email (in a new window by double clicking), it automatically opens a second window in 'write mode'.

I recently upgraded to Mozilla Thunderbird 102.8 Since then when I open an email (in a new window by double clicking), it automatically opens a second window in 'write mode'. This window contains the same message content, but also an error message at the bottom saying 'A unique identity matching the From address was not found. The message will be sent using the current From field and settings from identity <my email address>'. It sets up an email reply to be sent to myself. Clearly this is NOT what I want.