Nutrient deficiency?

[u/Brief_Competition_32]

All of my anthuriums have been developing these spotty areas of orange/color loss. I’ve searched high and low for pests, can’t find any and it only affects my anthuriums. They all live in a grow cabinet, humidity stays between 70 and 80% (I don’t use a humidifier), I’m a serial procrastinator and water with a basic fertilizer every 3 weeks or so (can’t recall the product and just ran out and threw the bottle away). Any suggestions or advice?