Beginning with Windows 10 20H1, the Windows OS assigns the graphics processor to use for various applications, and overrides any settings made in the NVIDIA Control Panel > Manage 3D Settings > Preferred graphics processor setting for that application.
You can change the GPU preference that the OS will use for an application from the Windows Graphics Settings.
If the OS does not have a GPU preference for an application, then you can specify the preferred graphics processor to use from the NVIDIA Control Panel > Manage 3D Settings > Preferred graphics processor setting.