I’m frequently going into settings to toggle the visibility of properties in a note. On most days, I prefer to have them hidden in the note, but shown in a side pane. This keeps a cleaner writing experience. But when I’m organizing things, I prefer to have them visible.
There is no hotkey to toggle the visibility of properties in a note.
Another approach is using a Templater template. Not the original request, but this flips between the Visible and Source setting for Properties in document:
Set it as a “template hotkey” for easy switching back and forth. The only thing I noticed is that as it’s a global setting all notes are affected. So, if you have two notes open it will change both. That hasn’t bothered me.