Hi @budbanditUk it seems to me to be a genetic alteration, very common in automatic plants, usually from the third real pair of leaves start to grow without defects, it will not affect the plant in any way. good luck mate 👍
Beautiful grow my friend. Blueberry Mango sounds like quite a strain. I'm jealous as I love those fruit strains ;) Enjoy the fruits of your labor and best of luck on future grows. 👍