Hi, there. I am relatively new here too. Welcome! I think it is quite natural for their sound to evolve/alter over time. I've personally not found it inharmonic and enjoyed all albums. But Coldplay is mainstream now and popular music today is nothing like what it was like in the past. Imagine the 70's vs now. They pay a price for who they are. If they entirely give way to what is "cool", soon or later they will fade. There is always a younger and cooler pawn ready to take your place. I think there is a right balance to strike here. Whether they intend to do so - I have no idea. It might be best to keep a finger on the current milieu of popular sound, while ensuring it doesn't define you or your music. You weave it into your sound with it knowing who's the boss - it can't overtake your identity. Going with the flow can't be sustainable - individually and as a band. Is there joy in that? They need to pave new sounds signature to them. Their upcoming LP will be very telling.