Odd looking lady

If your in DWC you need more air, if your top drip feeding your watering to often. Are you checking your pH regularly? I don’t see any recording of pH which is extremely important in hydroponics. Need to stay between 5.5 to 6.5 ( 5.8 and 6.0 being the best possible range )

Well, since you're growing in hydro, you can bet your booties it's not overwatering! In a soil grow, this type of condition would have been caused by over- or under-watering OR a nitrogen toxicity... so since it can't be either over- or under-watered, guess what .... I think you're overfeeding here ... Canna Start has an NPK of 2-1-2 which, on the surface, seems pretty minor but I think this lady is reacting to having too much of it in her system. I'd cut back on it for her if you can! Don't know if they're all on the same reservoir - if you are, it might be good to actually remove her from the tied-together system and get her her own bucket where you can adjust the nutes just for her... Each plant is an individual and will not always tolerate the same treatment others get even if they're the same strain from the same seed company bought at the same time... it's just like you can't expect human twins to absolutely identical in everything! This is a great little bucket - you'd only need to drill a hole in the lid to add/subtract water/nutes from... It's what I use and I love it... https://smile.amazon.com/dp/B01326JYTG? Good luck... she's definitely got a nitrogen toxicity working but it's easy to treat in hydroponics!