Is that a aerocloner or a small top feed hydro setup?
If aero…you check all your misters to see if they are spraying properly…they tend to get clogged all the time!
Just by looking at the color…looks to be on the dry side…also looks to be on the verge of Pythium(Root Rot)
When’s the last time you did a full clean out on the system?
EDIT: On a good note you can see fresh white new roots growing!