The WebClient Application Assembler %DLC%\bin\ProwcAppMgr.exe is signing files using the deprecated SHA1 instead of the expected SHA256

As stated in the following link:
https://learn.microsoft.com/en-us/windows/win32/seccrypto/signtool
the /fd algorithm option is now mandatory for the Microsoft SignTool.exe utility, and SHA256 should now be used instead of SHA1:

The Windows SDK, Windows Hardware Lab Kit (HLK), Windows Driver Kit (WDK), and Windows Assessment and Deployment Kit (ADK) builds 20236 and later require that you specify the digest algorithm. The SignTool sign command requires the file digest algorithm option (/fd) and the time stamp digest algorithm option (/td) during signing and time stamping, respectively.

If /fd isn't specified during signing and if /td isn't specified during time stamping, the command throws a warning, error code 0, initially. In later versions of SignTool, the warning becomes an error. We recommend SHA256. It's considered to be more secure than SHA1 by the industry.

as an example:
signtool sign /tr http://timestamp.digicert.com /td sha256 /fd sha256 /a "c:\path\to\file_to_sign.cab"

The now deprecated SHA1 was the standard to use to sign files when the WebClient Application Assembler %DLC%\bin\ProwcAppMgr.exe was implemented

Sign the files outside of the WebClient Application Assembler %DLC%\bin\ProwcAppMgr.exe tool using SHA256 before importing the signed files in the WebClient Application Assembler