I have noticed most FAs opt to mask up, but passengers have no such requirement. I like the system now, where the mask preference is left entirely up to the individual. Even now in Singapore, it's the same, though I've noticed the drivers on all of my taxi rides have remained masked, but there's certainly no requirement for the passenger.

PS - Even when masks were mandated, business and F, on CX anyway, pax were allowed to remove them when reclining one's seat.