To block 24H2:
reg add "HKLM\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /v "ProductVersion" /t REG_SZ /d "Windows 11" /f
reg add "HKLM\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /v "TargetReleaseVersion" /t REG_DWORD /d 1 /f
reg add "HKLM\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /v "TargetReleaseVersionInfo" /t REG_SZ /d "23H2" /f
reg add "HKLM\SYSTEM\Setup\UpgradeNotification" /v "UpgradeAvailable" /t REG_DWORD /d 0 /f