It would help if you can list as much possible about the grow that you can.
COPY/PASTE the below list into your forum post.
Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)
What strain, Seed bank, or bag seed
Age of plant
Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
Vessels: Pots, Grow beds, Buckets, fabric pots
PH and TDSof Water, Solution, runoff (if Applicable)
PPM/TDS or EC of nutrient solution if applicable
method used to measure PH and TDS
Indoor or Outdoor if indoor, size of grow space
Light system LED, MH/HPS/CMH/Fluorescents, or other
Actual wattage draw of lights
Current Light Schedule
Temps; Day, Night
Humidity; Day, Night
Ventilation system; Yes, No, Size
AC, Humidifier, De-humidifier,
Co2; Yes, No
If growing Hydro some additional questions:
DWC? RDWC? Autopots? Ebb and Flow? Other?
Distance of liquid below net pot (DWC)
Temperature of reservoir
TDS of nutrient solution
Always try to upload a clear picture in white light of any issues you may have to allow the community to assist you.
Looks like lights too close or cal mag or even just hungry. Just guessing without details.
Tough to know without more info. Fill out support tic. It will greatly help in getting assisted.
Solely based on pics they look hungry for some nitrogen and some calcium.
Update with details to help us help you better
I agree although plants sometimes exhibit defs in flower that you will not be able to correct. That said: need that Support Ticket.
I’m sure it can be a little frustrating not being able to figure out what’s going on, but honestly if you can take the time to fill out the above support ticket, it’ll make a world of difference.
So many variables to what could actually be wrong. Folks have been dealing with dif. issues for many years. There are multiple folks here that can help, but we really need to know details. Thanks and good luck. 
Here’s my take: if you really need help then pictures and a Support Ticket. Otherwise it’s just looking for confirmation. Not really into that.
Pull your reserve
Honestly it’s def light burn I’m not sure an experienced grower but I know what light burn is cuz I had same issue. It will discolor ur leaves turning them yellow n burn is the brown spots. It literally cooks em.
How far is ur light to pant