Rust/dead spots

It looks like underwatering and heat are the problems, along with light intensity. It may not need as much light as the others, so it's content just chilling at that height. If you have it on a table with the light above it, try setting it on something and putting it on the floor of your grow tent. That might encourage it to start growing vertically again. If you're new here, please select the answer that helped you out the most by clicking on the "answer" button underneath what the person said. If you have any questions, feel free to message me on here. You can pull up your messages tab by clicking on the little airplane in a bubble. It's located on the bottom-right of your screen. I hope this helps!

Maybe had a bit to much nitrogen, defo had some heat stress. Autos are quite sensitive and don't need much nutrition. Less is more if you get what I mean. I have been growing autos recently using biobizz light mix, doesn't seem to have as much nutrition in as other soils I've used and seems perfect for autos. Around week 3 in a light mix you can start adding nutes at max 1/4 strength and slowly build up, I doubt you will hit the manufacturer recomended doses of nutes as the plants throw a fit.

The plant is exhibiting a higher nitrogen level from the leaf curl. Maybe it’s from the Ph where they need to grow out of it. I almost never use veg nutes until week 5+. Looking like a little nute burn to me. Let the plant recover and grow out of it.