We purchased a home in southern California and are fortunate that there is a mature citrus tree in the yard. I think it's a lemon.
It was looking a bit sad when we moved in 2 months ago. I adjusted the irrigation so it got a little more water and it made a bunch of new leaves and flowers.
But almost all of the new leaves look spotted and not well formed.
My neighbor on the other side of our yard has several mature citrus trees with the same affliction.