Yup, it's suffering but ever so slightly. Which is good! You have time to fix before it causes any worse signs that can't be fixed by getting very dark shiny green leafs, which you have not got. Overall your plants look healthy but brother, drop the PH 6.3-6.5 max5.8- 6.3 is more desirable for coco. Soil is more forgiving with PH swings, try keep it in a even balance. And your PPM is like double what your plant at that age should be on. You are prob giving the right nutes and all but are experiencing nute lock, the claw, or canoeing of your edges upwards is an early sign to look out for before N tox gets too bad. Flush and feed water for a few days even a wk if using soil,, less if coco and restart core NPK+CAL+MICRO. Happy growing, good luck.