The rider must actually wear the jersey, either in the award ceremony at the end of a stage or in the race the next day.
The last time 5 riders wore the yellow jersey was 2020, and before that 2013. Most other years in that time span have seen 4 riders wear the yellow jersey.
As of the end of Stage 3, the count is 3: Bardet, Pogacar, Carapaz
maillot jaune
At the end of today's stage, Remco intentionally slowed down to stay behind Pogacar, and Pogacar couldn't help but grin and shrug when he saw Remco's move.
That said, Remco will absolutely attempt to take that yellow jersey, just didn't want it today. If they're close after Stage 4, they can differentiate themselves on the time trial!
Next couple of stages are too flat and there's too many sprinters to let the break go away, and Friday is ITT so GC guys will get even more difference. I think it's for GC guys from now on. Very unlikely Remco on Friday, if not then Jonas on week 3 if he gets to top form and Pogi cracks, but quite likely no changes from now on