Yeah, that's not good. Sometimes you can find it through some combination of ensuring that app is frontmost by clicking its icon in the dock, choosing "hide others" from its menu, and triggering "show application windows" in Mission Control (often ctrl-down-arrow, or a three-finger down-swipe trackpad gesture).
Due to the explosion in videoconferencing I've spent some time recently helping family set things up via remote desktop (I highly recommend Chrome Remote Desktop by the way, pretty easy to set up). This kind of thing is absolutely inscrutable to non-tech savvy people. All they see is that the computer suddenly stops doing anything but playing an annoying "donk" sound whenever they click and they have no idea that any of those features exist.
Really, Windows with its `window == app == taskbar item` approach is far easier to understand.
