There is a pin on the sidebar, but the sidebar still disappears. I know that you are trying to make it easier for people with small screens, but just let them un-pin the sidebar.
I have 28” monitors, so I usually have windows using ½ of my screen, but when I have 90 in a half window, the sidebar disappears even though it is pinned. This is annoying! Yes, I know that I can use the hamburger icon, but this is too slow. I want to permanently pin the sidebar.