@leocg that does work if you only have one social tab, but I have several. When you have multiple it opens one of them, and then if you hit the hotkey again it just cycles through the rest of them. It's a solution to the opening the sidebar, but not a complete fix unfortunately
Support here is terrible @dmccormick
Anyway, it does cycle between different but there's a way to hide and don't cycle.
When you press Ctrl + Shift + M, it opens and if you keep releasing and pressing M, you will cycle, correct? To close, all you have to do is release for a second (or less) all the buttons not just the M key and press them again. You will see that this closes the panel.
Unfortunately I don't see how to assign a hotkey just for closing, you have to do this