Strange artifacting when sharing screen

I've used Zoom for over a year now .  I didn't use as a host much this summer.  I just started classes again and I've been hit with strange artifacts wen I'm sharing a screen.  I have a MacBook Pro and a Macbook Air.  When I share a screen, my viewers get a dark shadow where the menu toolbar pops up.  Any other pop up like the video window creates the same dark shadow in the screen.  If I go to another window, the entire screen gets blacked out.  This didn't use to happen.