Light burn out Ca deficiency?

It looks like the begging of some type of lockout. Most likely your soil ph is off. Being a 1st time grower are you useing 100% happy frog soil? If so then you soil ph is to low. I would start with checking the run off water that come out the bottom of your plants soil. After you get a good ph reading then of ph is low you can flush soil with tap water usually ph around 7 to 8.5 and that will bring up the ph. If the ph is to high just flush with some 5ph water. If run off water ph is not the problem it's also possible you gave the plant to much nutes. Maybe wait a few days b4 giving more nutes it plants gets better you know it was you over did the nutes. If plant starts to get worse I'd suggest upping the p and k and maybe give it some kinda micros nutes sometimes when ph is around 6.5 micros can not be absorbed very well and I know when those are off it makes it harder for the plant to take up p and k

maybe it's calcium or magnesium. You can always see here what is most similar👇🏻 https://www.growweedeasy.com/cannabis-symptoms-pictures PS: check your PH too

I don't think its Cal deficiency. Sometimes I have these kind of issues when ph fluctuates.