It looks like over watering - meaning that you water too often, not too much!
Let the pots dry out until they're light when lifting them but the sol is still moist, then start the below watering regime, and you'll be golden :)
Fabric pots should be fully saturated with water when watering:
1. put the pot in a saucer so the fabric pot can do what it's supposed to do and wick up the run-off water
2. water with 25-33% of the medium volume
3. don't water again until the pot feels light when you lift it but the soil is still moist
Looks like you didn't fill the pots with more than 15-17L soil, so water each plant with like 4-5L.
Why are you mixing Hesi and Biobizz nutes?