help-plant issues--deficiency? lights? sick plant still yield? idk

You can certainly use the plant and get its normal yield, once any existing issues are delt with. There's another problem there besides the light & temps that looks like Phosphorus deficiency. Posting pics showing the lowest leaves would help to be sure.

 

P-def can look alot like nutrient burn. One of the main differences is that burn will be worse at the lowest & oldest leaves and get better on the way up. The fact that the necrosis is appearing on the middle leaves suggests Phosphorus deficiency. The reason for clear pics of the lower leaves is to be sure which it is.

 

This is one example of serious P-def. While the darker green indica leaves will present it slightly differently, note the similarity to your plant's condition.

 

Some of the best sources of Phosphorus include Bone Meal and high-P Guanos. They need to be made into teas for manual fertilizations. For ready-to-apply liquid fertilizer, Fox Farm's Tiger Bloom is a good choice for Phosphorus.

 

The main problem there is most certainly Phosphorus deficiency. In addition to the necrosis at the leaf tips, notice how some of the less damaged leaves have either deformed or stunted blades, usually on just one half of the leaf. That too is a very common symptom of P-def. Once you start supplying considerably more Phosphorus, the necrosis will stop appearing. The already damaged leaves won't heal, but the problem won't spread further.

Nitrogen deficiency doesn't usually cause any necrosis and typically doesn't damage only the leaf tips. It causes entire leaves to turn yellow or even whitish.

The leaves at the top reaching upwards happens when they aren't getting enough water. This water loss is sometimes caused by heat stress. Since you had mentioned that the light was too close & that you moved it away, I thought that issue may have been fixed. Watering cycles should go from moist all the way through the soil, to roughly the top third of the soil being completely bone dry. Keep an eye on the temps at canopy level and be sure to water thoroughly each time. It still needs to mostly dry out between waterings, but when you do water, all of the soil should be moist afterward. Don't be afraid to gently pull the plant from its pot after watering to see how well the unseen soil was moistened. You don't want to do this every time, but a couple times is fine until you know you're watering all the way through. Only pull plants in dim light because the roots don't like the light.