3rd week into flower and got curling leaves with s...

Too high temp, some leaves go taco. Plus obvious Nitrogen overfeed. If you in soil, slow down nutes for 3 full cycles, 4th start with 50% power. Those leaves are almost dead, they are crispy and too dark, so if all goes back to normal - you can pinch most damaged fan leaves, anyway theirs efficiency is very low. I would rise lights 20 cm or so for 4-7 days and see how they react. On last weeks before harvest you can blast them with light again if you want, not now. All the Best !