I burnt mine with too much UV experimenting.
Upper leaves curled, yellowed then brown at the tips.
They got worse after I shut the UV, and I cut them off. New leaves later grew to replace them.
Shut the UV, I wouldn't add it until you've gotten a trouble free harvest You've made so many changes, it's difficult to troubleshoot.
I have my UV on a separate trigger. It goes on for 30 seconds every 10 minutes, my idea was to give the leaves enough time to cool and recover between blasts. I still cooked them.
What PPFD are you at?