in Windows Server 2025, it appears that WinPE's C: assignment is now persistent

Question

Issue Observed:

• In Windows Server 2019 and 2022, even though WinPE initially assigned C:, Windows Setup respected Unattend.xml settings and reassigned C: to the Windows partition during installation.
• However, in Windows Server 2025, it appears that WinPE's C: assignment is now persistent, and Windows Setup no longer overrides it based on Unattend.xml.
• This is causing installations to assign Windows to a different drive letter (e.g., D:), breaking existing automation workflows.

Steps to Reproduce:

1. Boot into WinPE using an automated deployment environment.
2. Run diskpart and observe that WinPE has automatically assigned itself C:.
3. Execute an unattended Windows Server 2025 installation with Unattend.xml specifying that Windows should be installed on C:.
4. After installation, Windows is assigned a different drive letter (e.g., D:) instead of C:.

Questions:

1. Is this a known change in Windows Server 2025’s unattended installation behavior?
2. Is there an official workaround or best practice to ensure Windows Server 2025 installations always assign C: to the system drive?
3. Would Microsoft recommend any changes in Unattend.xml or pre-installation scripts to accommodate this new behavior?
4. Will future updates to Windows Server 2025 revert to the previous behavior where Windows Setup respected the Unattend.xml drive letter settings?