Yellow leaf

24/0 no, 18/6 yes. Look how little soil they have to grow in..............no wonder they are unhappy.........transplant asap! Those cardboard pots are crap too, they suck the life out of the soil and never break down fast enough to let the roots through if you do plant them out directly. Plastic pots are better, can be used for years and hold moisture properly.

Water logged and root bound the roots need some air . Repot the plant in a free draining pot and let it dry out between feeds

Too much light, it is stunted if that is 20 days. that could be main cause of the overall symptoms seen. Otherwise may need a bit more nitrogen. 24h is a bad idea unless you have a very underpowered light. DLI is the key, but right now you need to back off, drop to an 18/6 light cycle and wait for the plant to respond... once it starts growing again, re-adjust light based on the length of stem that forms between growth nodes -- not too stretchy, not too tight. Then, you'll start to get a better idea about whether this was killing it with light or if there is also a nutrient issue in your fertilization / substrate. read up on DLI. Daily Light Integral. The gist of it is enough. read the wiki. with ambient co2, you should start in the 35-40DLI range then observe and adjust light based on growth pattern explained above. knowing your umol/s of your light and size of tent can help you guesstimate "PPFD" which you can then reference with any DLI table with hours of operation to get yourself in that ballpark 35-40DLI... But as i said for this context, you first need to snap it out of the stunting from too much light. it may take a second or 3. Maybe, draw back closer to 25DLI for a while. if you have not been fertilizng, definitely start, but if it is not growing, go VERY light... once it starts growing you can slowly ramp up .. assuming you are soil, so the substrate should provide for a bit.

Pot too small. The substrate alone isn't even to the top So what you have here is a plant that's started eating itself to live You've put her through drought too often That pot size really you need 2l minium. Whats that like 300ml and only half full mate More bigger the more soil the roots have to spread out through not only taking nutes in the process but catching o2 which is key. Go big.

Probably needs some fresh good soil and more of it. Very little amount of soil it looks to be in. It’s looks like it’s not getting any nutrition from the soil or being fed any. No information here really to go off, so that’s my guess from what I have to work with. Also 24 lights on is so much. Why not 18/6 Good luck