Not a Planet?

My guess. First they have too much N, could do trick. Second you underwater them, all photos look like this. This could lead to proper salts build up ( hard to disolve ). Third they look either hungry, either having root issue, both look very not possible tho ... Forth wrong ph , sometimes even meter lies, are pots really light, or just top soil dries out ? That will give you answer. Either lockout from wrong ph or N toxicity. If they were heavy feeders and got used to, could ge hunger, but i give that 1%. Run off ppm and ph would tell a lot in such case, just take samples right.