So, I will say the bitch about watering is over and under look very similar. Your stems/branches are straight, but the leaves are limp = over watered symptoms. Now why they aren't taking up water is the question, because if you truly are only watering 1/3rd a gal every 2-3 or even 4 days, they shouldn't be over watered. How often are you watering/feeding? is it every other day at 1/3rd gallon? That would easily lead to over watered. Again digging for specifics.
Also, hell with the recommendations, I mean...they will keep you from killing a plant normally, but idk about helping it flourish because every strain and pheno can like slightly different nutes and treatment. That light looks 3 feet away, hell of a distance.. wouldn't hurt to find out rough ppfd that you're blasting over them. If you don't have the dollars for a legit one from amazon - $40-100+, I use the app Photone on a Pixel 6a with a piece of white printer paper as a diffuser over the face camera. I checked my lights which the ppfd chart they came with said at 100%, 18" away, 657 ppdf. Using photone setup as I said, it was reading 649-661. That's pretty damn accurate IMO for free shit. Anyways, I imagine as long as your phone isn't 4+ years old you should be able to get similar results.
TLDR: How often do you feed/water this 1/3rd gallon? Download Photone for free PPFD(google if you don't know) reading using front facing camera WITH a diffuser, white piece of printer paper works just fine.