Leaf problem on one of my clones

Leaf miners as everyone has said. Most of the maggots/larvae are out of the leaf. Just follow the trail from small to large and if you see a tiny opening at the end, the larvae is out and no point chopping the leaf. Also if you chop every leaf that gets a tiny nibble from a leaf miner, every new miner will be on a new leaf and you may run out of leaves like that. It's like throwing away a solar panel because a bird shat on it, really a bit of a silly overreaction. If you don't see a small hole at the end of the trail and rather a tiny dark spot, give the top of the leaf a light scratch and the larvae will pop out. The ones I get are bright yellow and easy to spot once out of the leaf. Squish it and problem solved. You'll often find a few hit your plant at the same time and then a break and might get hit again a few days or weeks later. The flies that lay the eggs only do so in quite specific conditions, so you get waves of them. Luckily they are not a huge problem and nothing to worry about, just keep scouting as often as you can.

Leaf miners are not as bad as thrips or aphids. If you don't want to 'poison' them, then cut the leaf an throw it in the trash.

Yes, leaf miners. Spinosad is an effective alternative to neem, which is also banned in my country for use on any crops intended for human consumption.

Not so much a disease but you have a pest called leaf miners. I would cut those leaves off so that they don’t spread around more. You can also try some insecticidal soap to spray the plant as a foliar spray to kill any eggs. Neem oil is also effective but I’m personally against the use of neem oil as it is banned in my country for crops intended for human consumption. Other growers have different opinions about neem oil. We all make or own choices on whether to use neem or not.