Zinc deficiency.
A dose or three of soluble trace mineral/trace element mix, available from any decent garden centre, and applied to the root zone should solve this issue.
Do not foliar feed, it introduces secondary problems, always apply supplements via the roots.
May take a few days to show results, but new growth will be ok.........damaged leaves might recover, maybe not, but they will still be doing their job, so please do not remove them for any reason.