Hi Joel,
According to my knowledge and experience, Microsoft Teams does not include a feature that displays the precise time stamp when a chat message is read or marked as unread. In addition, the capability to mark messages as unread is generally absent in Teams.
Microsoft Teams typically displays a visual indicator, such as an eye indicator, when a message has been read. This does not contain a particular timestamp. Additionally, when you initiate a chat, the blue dot typically disappears, indicating that the chat is being observed.
If you find this guidance useful, I'd greatly appreciate it if you could consider accepting this response. If there's anything else you're curious about or need more help with, please don't hesitate to ask.
Regards,
Dr. Gomathi S