Too wet and compact substrate maybe?

if cooc wait for top layer to change color, if 'soil' you want to wait for top 1" to dry before re-irrigating. just need more perlite or similar if it's not fluffy or not draining well enough. vermiculite is also a good option. vermiculite also adds some plant-available silica. (technically perlite has silica in it but it will never be plant-available.) go 50/50 with high water capacity soil... you can do less with coco, because it holds 2/3rds the water by volume. so 30% perlite or similar is fine in coco. any more is diminishing returns. this will improve root zone health. improved drainaage. improved O2 penetration. it will cause a little more frequent irrigations, of course, since it now retains less water per volume.

Too much watering BENY_TRUBY! You should weigh the pot before watering for the first time (imagine it weighs 4 kgs) and that will be your "dry" weight. It's really not "dry" because you have the initial moisture from your All Mix substrate, but that should be your "dry" weight reference. Then you should water again ONLY when the pot weighs around 4 kg and a little more depending on the size of the plant. My advice: Learn to "weigh" the pots by lifting them with both hands. With repetition and practice, you'll learn to detect when the substrate is "dry." One question, do you have perlite or arlite in the bottom layer? Because it should be arlite (the brown clay balls).