What is the reason why the leaves are like this?

It's marking about fertilization, water once with just water to remove residues and then water again with fertilizers rich in sugar like PK..

They are showing some signs of burning from excessive nitrogen (brown leaf tips), but the yellow edges would indicate a slight lack of potassium, something a P/K booster will correct very easily.

I would guess it's potassium deficiency. Just feed correct pH water and more flowering nutes and she'll be ok. Good luck growmie