That's too similar on individual tiles be the random patterns of lichen. and does look like a manufacturing defect of surface delamination.
Tiles tend to have the same colour dye throughout, and when the smooth surface wears, a rougher and lighter colour of the concrete becomes gradually visible and that fades evenly over time. Not localised streaks. However, Marley may use a colour slurry coating process over an undyed concrete core.
Marley give a 15 year warranty if their whole system was used, but also mention a "60 years plus" performance. But a streaky faded roof tile may still keep the water out and so be classed as "performing". But you could give it a try with a complaint.
Otherwise check any other warranties with the build, but NHBC won't cover this at nine years.
Too late for a latent defect claim.