I noticed more these days that comments are disappearing. This has happened to me twice in the past 2 months. I recently got a comment notification via email (see screenshot) and when I went to the task it disappeared. The person who left the comment is a project collaborator which as far as I know does not have permission to edit or delete their own comments. There's also no trace of the comment in the task activity stream.

This is really bad and makes me lose trust in the product since a lot of comments are discussions that are important to the whole task. Losing that context and answers could be devastating.