The symptom of this was freezing streaming that Apple Support took 1.5 hours to diagnose and another hour to attempt to fix.
Apparently, MacBook Pro 16" 2019 comes with two graphics card: the advertised ATI Radeon and an integrated one by Intel. ATI Radeon is supposed to be much better; thus MacBook Pro is advertising it; why do they have the integrated one I don't know.
Anyway, my brand new MacBook (Catalina) was setup to use the integrated graphics card, while the more powerful ATI Radeon was staying idle, doing absolutely nothing. As the result it's freezing for a fraction of a second every few minutes.
Did anybody else see this? If you have a MacBook Pro, and in About This Mac / System Report / Graphics/Displays see multiple graphics cards, which one is used by MacBook, according to About This Mac / Graphics?
More importantly, is it possible to reconfigure which one is being used? Apple Support tried things such reinstalling OS, which changed absolutely nothing.