Looks like nute burn. Your nutrients are more potent than you realize, you might only need about half as much as what you’re given them. Otherwise there doing really good I’d say. Final note, I’d check the pH of your root zone, or simply next time they need water, see maybe you can rinse them a little bit, just water so your getting 25-50% of what went in to come out the bottom. I’ve noticed when feeding heavy enough to cause nute burn, I also see a significant drop in my soil pH. Simply giving them a good flush can help to wash away the leftovers from previous feedings, and restore your pH a bit. There are flushing agents you can use as a means of rinsing the root zone with less water, things like the foxfarm sledgehammer. I think GH has a rinse. Otherwise you can just run lots of plain water. If you can check your soil pH, you might find that it’s okay, and all you need to do is maybe skip a feed.