Is this lightburn?

Yes that is a light burn or rather scorched. Somehow You need raise the lights at least 10 cm, 15cm would be better and 25cm golden. If not possible due to head room, You have a problem. Use some ties to pull the plant top away from the light source, like anchoring to the sides of the tent or something. Thumbs up and next time remember Hazez tend to strech a lot :-).

i think its a nitrogen burn.... but im not an expert

Hi mate, I think your plant is looking awesome. I believe what you're seeing is a late stage potassium deficiency, maybe even a little zinc is needed. This far into flower it may not be worth worrying about. I don't think it is heat or light stress but it wouldn't hurt to lift the light a couple of inches to see what it does. I noticed a huge difference in my grow with a little extra height between the light and plant. I hope this helps, good luck and happy growing