How do I bring back the Windows 7 Sound Recorder on Windows 10?

Try3 said:

It is the audio driver rather than the OS itself that allows or disallows Stereo mix.

Stereo Mix does need to be enabled in audio properties but Voice Recorder on W10 and W11 does not support it. Only records from microphone input. See next update

- - - Updated - - -

I take my previous comment back. If you enable Stereo Mix and set as the DEFAULT recording device, Voice Recorder WILL use it even though the app refers to the recording source as 'microphone' and still displays a little 'microphone' icon for the record button. You need to enable access to the microphone in app/device permissions. Voice Recorder is just remapping everything as 'microphone' but it is actually the Stereo Mix channel. Only outputs to .m4a format though.