just looking at the replay of when Maverick Vinales came off when his motor/gearbox seized and threw him off near the end or the race. It looks like the visor came off his helmet ?! I have rerun start/stop a few times and it looks like the visor shaped bit of tinted plastic came off his helmet. His head hit the ground and from that point the tinted bit of plastic is seen flying off - can't see that it is part of the bike. That can't be right having a visor come off - maybe I am not seeing it right ? Very poor if it did come off.
Apologies, in answer to my own question - I think this bit of plastic is actually the aero spoiler from the back of the helmet that has come off and not the visor itself.
IME, it’s not uncommon for the visor to become detached from the helmet when a rider falls off in a race, especially if the rider head butts the tarmac or cartwheels through the gravel. Andy