I have to say I've never used ProBuilder before, but according to some tutorials, in order to be effective in its use, you also need to install ProGrids. One of the first things I noticed after installing 2020.1, are the "toggle grid visibility" and "toggle snap" buttons, on the Scene's tool bar, so I didn't install ProGrids. I've been using ProBuilder for a couple of hours, and it looks to me like the native grid system covers any aspect you may need. So if ProGrids becomes obsolete on 2020.1, then why I steel see if on the Package Manager?... or what's the reason to keep it alive?