New to growing autoflowers

as said in the title, new to growing.. got 3 fastbud autos on the go.. so I’ve been hand Feeding them from a 1ltr watering can, following the nutrient line feeding schedule (https://www.shogunfertilisers.com/en/growing-information/feed-chart-calculator/coco/1-litres/250-ppm-eutech/standard/

so far 2 of the plants have been fine, but one the tips on the upper leaves are starting to yellow.. my first time growing So any problems is straight to panic stage! and also new to the forum So sorry in advance if I’ve done anything wrong. Pics below of the yellowing plant, any tips, tricks or advice would be highly appreciate. thanks!