The two “buttons” on the top right: the overflow (
…) and the hamburger (
☰) menu behaves differently. And the hamburger menu is used to not change the layout.
If you would like to retain a quick toggle for showing/hiding the right sidebar (which is btw the first menupoint in the overflow menu), then please use a different icon. For me a left pointing chevron (
«) would be more natural for that kind of functionality.
Or with the Toggle Right sidebar button removed from the main UI to declutter the UI (but here, the three-dots menu is opened):