I would look under your leaves to find pest. This is a sign of pest. To make it easier to identify cuz it's hard to see in your pic is go to this website https://www.growweedeasy.com/bugs-pests-symptoms-marijuana-grow. They have pictures of what certain pests do and give great explanation plus how to resolve.
Hello there! It could be pests as well as mag def. But looks like it could be pH levels, try checking using a regulator, but essentially you'll want them to be around 6.5 đ
i would look under magnified glass to see better but from what i see it cold be mag deficiency i do not see what you are using as nutriment or water ph