Microsoft has made it possible to easily relax the PowerShell throttling in your tenant

• Open the Microsoft 365 Admin Center. You need to be using the new Admin Center - make sure you've enabled "the new admin center" switch in the top right of the home page.

• Click the Need help panel in the bottom right hand corner
  
  
  

• Enter "PowerShell Throttling" in the Need help section. This will launch the Exchange Powershell throttling wizard

• Click the Run Tests button. Office 365 will run several diagnostic tests to confirm that throttling isn't already disabled in your tenant and that you haven't already completed this wizard in the past
• Once the diagnostics have run, click the Update  button.

• Exchange Online Powershell throttling will now be removed