Hey bro it looks like an advanced deficiency but stuff like that could also be caused by lockout/toxic stuff or gross pH mismatch so it would be nice if you could give out as much info as possible so people can put you better into the picture of what might have happened. Like pH in, nute strength EC, potsize, watering frequency, water analysis. Any older photos of it when the thing started?

Use more nutes. They look way underfed to me if you’re not overwatering.