There is something weird with comment cards and notifications. I got a notification for comment card that I created. In the email, it had the name of someone else as the author. Also, the search dialog, it also initially indicated that another user updated that card. When I visited the card in the space and toggled the comment visibility, it corrected the author back to me.
so maybe the bug is that when another user opens a comment, it changes them to be the last updating user?
(I can try to fill in more details when I have time)