Full Screen Program will not allow switching to any other program

This was fine (-ish) in 20w19a.  In this version I cannot activate any program other than minecraft (using alt-tab or using windows key) while minecraft is in fullscreen mode.  This is true while launching and while in the menu screen before loading a world.  (The program freezes when trying to create a backup world, so I have not been able to test in-game bahavior.)