When creating a maniphest query and limit it to projects "viewerprojects()" that works for "normal" users.
But for newly created users that have joined NO PROJECTS AT ALL:

• expected: see no tasks when running the query
• actual: see ALL tasks that are visible to the user

as soon as the user joins any project, most of the previously listed tasks vanish from the resultset and only tasks from that one joined project are returned.