AutoAddTeams.ps1

Connect-MicrosoftTeams 
Get-Team -displayname "YourTeamName" 

while($true) {
    #Get Teams users, the one's that haven't left...
    Get-TeamUser -GroupId (groupidhere) | Select-Object user | out-file C:\PreAddUsers.txt
    $PreAddUsers = get-content C:\PreAddUsers.txt
    
    #import the list of users who should be in the Team, add them
    import-csv -path "C:\Thisisthelistofusers.csv" | ForEach-Object {Add-TeamUser -groupid (groupidhere) -User $_.email}

    #Now, get the list of users in the Teams, for comparing. 
    Get-Teamuser -GroupId (groupidhere) | Select-Object user | Out-File C:\PostAddUsers.txt
    $PostAddUsers = get-content C:\PostAddUsers.txt

    #Compares the two lists for outputting
    Compare-object -ReferenceObject $PreAddUsers -DifferenceObject $PostAddUsers -PassThru | Out-file C:\UserDiff.txt 
    $output = Get-Content -path C:\UserDiff.txt -raw

    #writes the lists of users who were added back to the Team, along with the date. Then will wait for 6 hours before running again.
    Write-host "$output" -ForegroundColor yellow
    write-host (get-date).ToString('T') -ForegroundColor green
    "Users added were $output" 

    start-sleep -seconds 23200

}