Im not too sure, because of the yellow light, but the leave just looks like the plant is missing nutes or, was at some point. Maybe Soil formula was changed a bit? Do you use any bottled fert? If it is not the missing fert, something causes a cal/mag lockout, maybe caused by too much cal/mag. Fert needs certain ratios to work well with plants especcially cal/mag. So if you add single-fert. needlessly like cal it has a contrary effect. So if you bring cal/mag into the earth without knowing this can cause lockouts.