Wtf did I do?

can anyone help me understand what’s going on with my plants, what I did to cause this and how can I fix it?
Background:
5 gal pots in a 50/50 coco perlite mix
2x4 tent
600w led
Day 28 veg
I worked my way up to 3-3.5g of mega crop/gallon
Feed every 3 days
The last 4 or 5 days were 90 degrees where I am and during that time the temp and humidity in the tent got as high as 102 degrees and 57% for about a day. Since then I’ve been able to fail it back down to about 82 degrees and 45% humidity. It’s been pretty stable since then.
I noticed the problem last night when I went to feed and I thought it was a cal mag def or a nite def. so I added 3/4 tsp calmag to my feed also.
I came here to check earlier today and I can’t see any progress.
What is it? How can I fix it? Should I pull or cut the dead leaves from the bottom or leave them there?

More pics

Looks like nutrient burn to me.

Also maybe a little ph problem what is it reading at?

You won't see progress.... what you wanna see is the problem not progressing,getting worse

Poor drainage?