Description
The macOS window restoration never really worked, and that is still not working at the moment, although after all these changes (and knowledge gained) it will be easier to achieve it, if needed. It's a rather low priority issue, as the only way to achieve it is to have something open and CMD+Q the app. If all the windows will be closed, one by one, we get back to the "initial" one window mode after relaunching the app, so that path is working as expected.
The alternative (and hell lot simpler) solution is to have all the windows/tabs closed, regardless which path the user is taking to exit the application. This way we will only start with a single window "initial" state after relaunching the app. Currently it's possible to open several windows, press CMD+Q, and after relaunch we will see the same amount of windows, but all of them will be empty.