Help please. Megapot system (autopot) installed and lights increased to 600W from 400w. Plants looking really healthy before these changes.

Luckily it's a fabric pot, which dries out quicker anyway. Maybe let a ventilator blow just on the pot. I also put the pot on a tray with perlite (or maybe those clay balls) before, which helped get the water out quicker.

Uptake of water at the roots is determined by the loss of water through the shoots, and the loss of water through the shoots is determined by how much water is in the air. Lack of oxygen in rootzones grinds production to halt. Every leaf sags drops heavily laden with excess water but no way to transpire.

More is not better. You want the "right" amount of light. These are clearly being blasted by too much light. Read about daily light integral (DLI). The wiki is sufficient. You don't have to memorize the math, but you should understand the gist of how it works and how to properly measure it.

Yes.