This feature in powered by Microsoft Whiteboard technology and works with just one person in charge or in collaboration with others.
Annotation—powered by Microsoft Whiteboard—helps you collaborate on things like a design or presentation while sharing your screen in a Teams meeting.
One of the fastest ways to get work done is to get together on a Teams call, and co-author on a document as you chat and work together. This update is an exciting addition to this way of working.
https://supersimple365.com/collaborative-annotations-on-presenter-shared-screen/