Microsoft yesterday announced some changes to the Windows Autopilot sign-in and deployment experience. First, Windows Autopilot no longer allows pre-population of the Azure Active Directory (Azure AD) User Principal Name (UPN). When you want to re-enroll a device after deployment, you need to delete the device record in Microsoft Intune All Devices blade before re-deploying a device. Microsoft mentioned the following as the reason behind the changes:
We made the changes because the reuse of hardware components, such as motherboards, or the refurbishment of devices without deregistration could potentially cause an issue if the device identifier can still be linked to a previous company. Hardware is being reused at record levels, partly due to the pandemic’s effect on global supply chains. While this reuse helps meet corporate sustainability goals, we had to remove the could and ensure no issues were caused. To date, we have found no evidence that anyone has used this to their advantage.
You can learn more about the changes from the link below.