Clones turning yellow at the top

You should soak cubes at 5.0 before use…then 5.8 ph use plain water and root hormone only till you see roots 5-7days then light nutrients

Its taco tuesday🌮im guessing you baked them under your light

Es ist völlig normal das Klone gelbe Blätter bekommen und etwas kränklich aussehen, denn sie können am Anfang nur auf die Reserven in den Blättern zugreifen. Gib ihnen Zeit und halte die Luftfeuchtigkeit hoch, die Würfel sollten nur leicht feucht und nicht nass sein. Besprüh dezent die Blätter, das genügt zur Bewässerung. Ein paar Tage nachdem sich die Wurzeln gebildet haben, kehrt die Vitalität zurück. Viel Glück!

I found that when that happens, the mother or donor plant was likely already in poor health. It might not look it, but I’ve noticed that to be the case. Could be too much light also

How many watts of light are you running on them? I would guess it's too much light power. Clones root great with low temps around 75f and low light power. I use like 20 watt 6500k CFL lights to root clones. Too much light will fry them.

Half of them look dead already, it's some imbalance, I am not a pro , but one thing sure, get ready to strip that/those plants more if you need clones ... Hope somebody will guess your issue. I was putting mine into water, just in glass for a week, sometimes I was adding a bit of BioHeaven and sprinkling them with cinnamon when had no money and mycorrhizae when I had few bucks ;) and straight to soil after. Worked really well. All the Best !!!