The ProblemSomething must have corrupted my Windows 10 windows size settings, such that whenever I open file explorer, it opens in too small a window. When I resize it, I expect that Windows will remember the size I chose, but it doesn't. I figured out a workaround which is just a bit flip.
The SolutionGo into taskbar --> taskbar settings --> taskbar location on screen --> change the location to top or left --> now change the location back to where you wanted it (mine is bottom).
It appears that the toggle accomplished by this fixes the problem.