2024/01/04 : I get the base now, with 8 futur colas and the height is just 13,5 cm!
I let it rest under SF300 used for germination/cloning for a few days as it doesn't look so good for now.
Lowest fan leaves were kept to help while transplant/topping shock : yellowing and deficiencies everywhere.
On the upper floor, my 8 new mates and their leaves look good so it may be OK.
2024/02/05 : My pHmeter was decalibrated, showing about 0.20 to 0.30 under truth. After recalibration, just to be sure, I did a quick flush with pH=6.20 rain water (1 mL/L calmag + 0.5 mL/L tracemix).
2024/02/07 : I sprayed with BoomBoom last night to help with recovering and it looks better. I removed lowest fan leaves and first nodes from the middle. I reshaped blueberry with "Js" to keep each branch apart. It's looking as I wanted and now the height is 12,0 cm. Still under SF300 with DLI = 26 (@20cm / 400 PPFD / 18h).