Maybe a third version of I Corps, as this example has a coloured surround on a Lynx belonging to RCD:
The above may have influenced what I perceive to be seeing on the II Corps. The second photo linked in the initial post starting this thread might be something, or just shadow or even garbled pixels.
Another possible photo is this one, just seems to be a lighter line separating the diamond from the horizontal red bars:
regards,
Jack