Leaf tip probably touched the soil.
I was more worried about the browning in the center of leave and the curling
I’m guessing overwatering and heat stress. Id say fabric smart pots are the way to go. .
Perhaps a list of things are in order? Soil, watering, ph etc. So we can better understand whats happening?
Fox farm ocean Forrest
Purified water ph to 6.5
Water every 4 days
Feed fox farm grown big once a week
Ok that may be an issue? Your soil is already pre loaded with nutrients, normally folks around here that use Fox Farms soils refrain from any additional feeding until at least week 5. Perhaps you use straight ph’d water for a bit and see what happens? Perhaps, you can think about potting up a plant also in fresh soil and that will give you an opportunity to inspect the roots as well as give them something to reach into. Make certain your pots have excellent drainage, that cant be over emphasized.