yellowing leaf tips and curling up

I am currently on day 51 of flower.
Growing in Coco under Cob Led light.
Leaf tips are turning yellow on the outside and leaves are starting to curl upwards.

Any ideas would be really appreciated. My last crop did exactly the same.

Looks like problem is related to nutrient deficient. Although looks yum.

It looks like nute burn but nothing to be concerned about unless the other leaves do the same thing.

looks like you may have some heat stress going on as well, which can exacerbate nute burn issues. the curling of the leaves near the tops is whats making me think this.