Information
This policy setting controls who has access to read and write chat messages during a meeting.
Ensuring that only authorized individuals can read and write chat messages during a meeting reduces the risk that a malicious user can inadvertently show content that is not appropriate or view sensitive information.
Solution
To remediate using the UI:
 - Navigate to Microsoft Teams admin center https://admin.teams.microsoft.com .
 - Click to expand Meetings select Meeting policies
 - Click Global (Org-wide default)
 - Under meeting engagement set Meeting chat to On for everyone but anonymous users
To remediate using PowerShell:
 - Connect to Teams PowerShell using Connect-MicrosoftTeams
 - Run the following command to set the recommended state:
Set-CsTeamsMeetingPolicy -Identity Global -MeetingChatEnabledType "EnabledExceptAnonymous"
Impact:
Only authorized individuals will be able to read and write chat messages during a meeting.