I just noticed this, what should I do? Sorry for the vague question but I can't find any good articles on what this is.
Everything I find starts the same way "top 8 reasons for brown leaves". Then says too much water, not enough water, too much light not enough light too much fertilizer not enough, wrong kind of fertilizer and so on and so on. That isn't helpful! Do I just have to guess? Why is all plant knowledge basically voodoo?
I'm tempted to take a cutting so I have a spare to try again if it all goes wrong, but the plant only has 5 leaves, so I'm stressing out.
Get a magnifier, look on the underside of the leaves for very small cigar shaped insects. If you see any, they are thrips and you are in for a headache. Get a bottle of Captain Jacks Dead Bug Brew or a spray with spinosad. Spray the affected plant and any other nearby or other soft leaved plants once a week for 6 weeks. That's what it takes to get the adults as well as the larvae that hatch out from eggs in the leaves. Thrips fly so treat as many plants as is practical. For larger collections you can release beneficial mites which eat thrips.
I hope it's not thrips.