Convert large number of Public Teams to Private

Curious_Kevin16 

 You can use the teams powershell module sothing like this 

# Install the MicrosoftTeams module if not already installed
Install-Module -Name MicrosoftTeams -Scope CurrentUser

# Import the module
Import-Module MicrosoftTeams

# Connect to Microsoft Teams
$credential = Get-Credential
Connect-MicrosoftTeams -Credential $credential

# Get the team you want to update
$teamName = "Your Team Name"
$team = Get-Team -DisplayName $teamName

if ($team) {
    $teamId = $team.GroupId

    # Update the team to private
    Set-Team -GroupId $teamId -Visibility Private
    Write-Output "The team '$teamName' has been updated to private."
} else {
    Write-Output "Team '$teamName' not found."
}

# Disconnect from Microsoft Teams
Disconnect-MicrosoftTeams

For each team you set as private, you are probably going to have to set its membership as well here is how you can do that https://learn.microsoft.com/en-us/powershell/module/teams/set-teammembersettings?view=teams-ps add Set-TeamMemberSettings after Set-Team visibility

hope this helps
D