New Teams Disappears

HelloRocioA 

welcome to the Microsoft community, My name is Recep I'll be happy to help you today.

I understand that you no longer see New Teams in All Apps list and you have to turn the toggle on and download again to use. 

Please note that there are two methods to manage and configure the new setting either via Teams Admin Center or via Teams Powershell.

Configure setting via Teams Admin Center

Use the Teams Admin Center to manage the visibility of the toggle on a per-user basis.

1. Sign in to the Microsoft Teams admin center.

2. Select Teams>Teams Update policies from the left pane, as shown below.

3. Select Add to create a new policy or select an existing policy to open Update policy.

4. Name the update policy, add a description, and select the setting for “Use new Teams client”, as shown below. The setting UseNewTeamsClient can be configured to one of the following possible values:

5. Once the policy is defined, you can assign it to a specific user or user groups by selecting the Policy name>Assign users>Manage users. Enter the user to add and hit apply (as shown below for Contoso sales policy)

6. Once the policy is defined, you can also assign it to a specific user via Manage users under Users> Manage users drop-down.

Update policy setting using this method takes effect within one minute without user having to restart the app.

Control setting via Teams PowerShell

Here are the steps needed to configure this setting:

1. Import the latest Teams PowerShell cmdlets (require version 4.9.1 or greater) by following Manage Teams with Microsoft Teams PowerShell instructions. Direct link: PowerShell Gallery | MicrosoftTeams 4.9.1.

2. Connect using an admin account using this command:
Connect-MicrosoftTeams

3. Once connected and logged in via PowerShell, you can explore the list of related commands: Enter *-CsTeamsUpdateManagementPolicy and tab through the commands (tab key).

4. Use the following commands to change the existing Update Management policy to opt-in the
assigned users to ensure that they have the option to try the new Teams:
Set-CsTeamsUpdateManagementPolicy -identity <new_policy_name> -UseNewTeamsClient UserChoice

Example:
Set-CsTeamsUpdateManagementPolicy -identity MySetting -UseNewTeamsClient UserChoice

Note: this method (existing policy modification) does not take effect immediately; please allow up to 24 hours for the change to propagate to users. Users do not need to restart the app, but specifically for opt-in, they will need one restart following a fresh install to see the toggle.

Use the following commands to deploy a new policy to opt-out a specific user from seeing the
toggle:
New-CsTeamsUpdateManagementPolicy -identity <new_policy_name> -UseNewTeamsClient AdminDisabled
Grant-CsTeamsUpdateManagementPolicy -identity <user> -PolicyName <new_policy_name>

Example:
New-CsTeamsUpdateManagementPolicy -identity MySetting -UseNewTeamsClient AdminDisabled
Grant-CsTeamsUpdateManagementPolicy -identity email address removed for privacy reasons -PolicyName MySetting

Note: this method (new policy assignment) should take effect within one minute. Users do not need to restart the app.