Yellow spots

I do not think it is an insect problem, if it was insects, there would be damage all over the plant, not just at the end of the leaves.

Could be a pH problem or a feeding problem. But without a diary and/or a lot more info about what you may or may not be doing, it is almost impossible to give meaningful advice based on one random picture.

My friend, take a good look with a microscope to see if you spot any pests under the leaves... it looks like spider mites... use some Neem Oil now before it starts to flower. You'll see it cleans up and gets back in shape... if you add a little Advanced Nutrients Rhino Skin, you'll see that the leaves will become thick and the aphids and spider mites won't be able to penetrate the leaf walls...💪✌️🕉️👍