I'm only telling you what I've been told by the guy at UA
Perhaps regulations have changed regarding Europe and in European comps a third kit is needed and it's easier to get everyone to have one now incase of future qualification. I don't have UEFA contacts just kit ones.
Old man Steptoe has told me a Red /White home with a sort of stripe, take that whatever way you want with a plain red back.
Blue and Yellow away and that hideous light red dark red is 3rd kit as per regulations regarding Europe.