I don't think there is a defined list as things can change.
You cannot use it at the Swan or Dolphin restaurants. I am not aware of a restaurant inside the parks or a Disney owned hotel that would decline them. Some of the third party locations at Disney Springs may not take them. I have heard that Chicken Guy does not, but that was not from personal experience.
FWIW, I've definitely been able to use a Disney gift card at Chicken Guy. Sometimes I've run into situations at Disney Springs where they have the magic band/Disney gift card reader turned off and can't accept payment that way.