The arcpy.management.CalculateField() function uses the active portal connection in ArcGIS Pro, even when run in a standalone script, and the script signs in to a different portal using the SignInToPortal() function.

Información adicional

Solución alternativa

Use the URL+Token generated from the SignInToPortal function to add the layer to a map stored in a .aprx file, and run the calculation based on the map layer. Since the layer is authenticated with the token, then there is no need to authenticate further with the portal.

Pasos para reproducir