The yellow looks identical to this season’s Volt. I don’t understand why white/light grey isn’t an option like it used to be a few season’s back
When so many keepers now wear either lime green or bright yellow, those two colors or colors close to those shouldn't be options for referees. Here in the US, two of our colors are lime green and yellow. If we are following strict letter of the law and wearing a color that differs from keepers and field players (Yes, I know the rule technically says that keepers are supposed to change to a color that isn't the same as field players and referees, so they are supposed to change. However, what sensible referee is going to force a keeper to change?), then we would hardly ever wear green or yellow. Plus, I've seen some teams wear volt yellow, which effectively rules out green and yellow from our color choices.
My son's basketball team wears a gray that's just a little lighter than the shade to which I linked in my post. In the last two years, they have worn that gray all but three times they have played. They just never have to wear their white uniforms because that gray contrasts with white, black, and every color in between except gray and silver.
I think if you gave referees three colors - medium gray or light blue, black, and pink - and made it a requirement that if there's a conflict that goalkeepers needed to change, you could make it a lot less expensive for referees (especially in the US, where we don't have the "referees wear black" requirement that many other countries have for grassroots games) to get started. I've never understood in the US why our five shirt colors are colors that many other teams and keepers wear (well, except for lining the pockets of the referee suppliers . . .)
EDIT - This is basically the color of my son's gray basketball uniforms - You could wear this for any normal color matchup (red vs black, navy vs green, yellow vs royal blue), etc. Except in rare cases, you could get away with wearing a color like this even if one of the teams is wearing white.