(05 Oct 2021, 1:38 pm)Keeiajs wrote It might be to connect with the Xlines in that type of colour, but I would rather a green maybe.

Probably some stupid reason like that, like they said the orange and white road stripes on the updated 10 livery is correspond to the XLines 84/85.  
The reasoning is not at all obvious, especially to the public so why not just pick colours that go together well.