Nutrient deficit?

As said already a lack of information and diary makes it hard to answer but going on your previous diary you are using bottle nutes and in pebbles so I'm presuming hydro or at least an inert media. I'll answer going on this. Check: pH wants to be 5.5-6.5 ideally 5.8-6.2. Temps around 70-80 Rh around 60 Solution temp of hydro 19-21°c Feed with calmag Check EC of water first. Below 0.2 or ro definitely add calmag 0.2-1.0 may do without I've 1.0 I'd not use. If using half strength An B try upping a bit at a time in case of underfed If using full strength then consider lowering it as it could be overfed. Good airflow. If a deficiency then it's a mobile nutrient being the bottom leaves yellowing. Make sure the nutes are in ratio and not too strong not too weak. If they have right amounts available then make sure they are delivered at the right pH. If I'm DWC then take the EC reading. The next day check again. If it's gone down then you need to increase it. If the reading has gone up then the plant has taken more water than nutrients which makes the solution more concentrated. If it's the same then that shows the plant is 'eating and drinking' equally. Just check all parameters. Doing a diary would help anyone trying to help you.