... as in what exactly are you feeding (brand, schedule, dosage, ppm's --I see that now),... but I think this is from a pH hiccup, locking out P temporarily,... easy to to because the color/dropper type testing isn't very accurate, and in hydro, that is everything... it's not very flexible in nute availability--->
View attachment 987996 ..... in hydro, it's pretty much mandatory that you have a decent pH meter, just the same as a TDS/EC meter,... current ppm seems OK...
.... don't nip off leaves unless there's a very good reason, removing them don't fix anything, and can make matters worse; leaves can store certain mobile nutrients as reserves,... P is one of those,.... plus on a small plant, you taking away proportionately large amounts of transpiration and photosynthetic surface area,...