what to do?

Also have to do my last advice or anyone's with caution. I'm am not positive that is the issue, since I can not see your plants/environment. and if it not and you bring the light closer that could only make things worse. When you are unsure and trying to figure out what's going on try not to change more than one variable at a time, or a little as possible so you can pinpoint what's happening in that moment. Simply adding more light is an easy test, just need to monitor it. if that's not it i would be looking how much water they are taking in, and soil/rot zone oxygen availability. Environment is the next thing to look at. I see you night and air temp are the same? its good to have a little bit of a differential. Anywhere from 68-76 at night and 74-89 during the day most plants will adapt to. and somewhere in the middle is the sweet spot. 83 degree days and 72 degree nights in veg then 78 degree days 68 degree nights end of flower. you can go beyond those numbers in some cases it depends on relative humidity.

How much light are they getting. Inadequate light can cause all sorts of problems. I notice lots of problems clear on with certain things just from giving plants more light. I just took a look, and i think that's probable. try bringing you lights a little closer and see if they green up. if they have perfect watering conditions they are going to require more optimal lighting to keep up.

Since you are using Biotabs and Blumat (which means continuous/frequent watering), it's very common to have the soil moisture constantly on the higher side, which can cause minor nutrient uptake issues or calcium/magnesium lockouts even if you think it's not pH or overwatering. At day 25, autos grow fast and might need a little extra cal-mag or a gentle boost if the tabs haven't fully broken down yet, especially with Blumat systems keeping specific spots wet.