This is the only way to somewhat "mask" when playing a woodwind instrument.
The player's breath literally escapes out of the first open hole in the body of the instrument, so it has to be bagged.
Would also need to be done for clarinets, flutes, and so on. Brass instruments only need a hairnet style cover over the bell. Brass players however, would need a designated area to empty the spit out of their instruments normally emptied by opening one of various "spit valves."
Band is hard to do safely during COVID.