I was doing some raids and I saw that tiles on board are slightly darker when there is enemy/defence “turn”
My turn (I have blue tiles darkened by options):
Enemy turn:
The difference isn’t big but I think its fairly new right? Or was I blind for few months/years?
It looks like you made a change to the color blind settings. Check those.
It was in the same fight, It changed by itself. When Lianna fired colors went back to normal. Only my blue tiles are changed by color blind options.
Both pictures look the same to me?
Looks to me like the whole second picture is slightly darker, not only the tiles?!
Maybe the phone changes display brightness every now and then for better visibility depending on environmental light/darkness. 
I turn off automatic brightnes change
Ah I can see it. Also brightness shouldn’t effect pictures taken. Not really sure what it is though. Good luck.
After reading the post, I was doing some farming, and I watched for it. OP is correct; the stones dim when it’s the defense’s turn. The visual cue is interesting, but really subtle.
I think the intent here is to indicate that you can’t move tiles during the defense’s turn.
