No clue what im doing

I have no idea what Im doing and need some help.
I have Bubblegum autos on week 10 temps kept at a steady 72 600w lights on a 16 on 8 off schedule one plant looks great the other the leaves are turning brown. what is wrong and what should I do to fix it?also how much longer you think I have until harvest?

What are you feeding them?

Are they all 3 fingered leaves? Strange

just some 4-4-4

Hmm never even realized that. this plant grew drastically different than the other one. This one is very short the other is alot taller and larger leaves

Looks like it might be calcium or magnesium deficiency. Pick up some calmag and you should be good to go.
I had a similar issue around week 10 as well oddly enough.

Thank you I will pick some up