ironf1stanswered grow question 2 years ago Yo bro, im a noob myself right before harvest but in my opinion it looks like a nutrient burn, if it was light, all the sides would curl up, not only the tips.
I've checked your diary and the auto strains are a bit more finicky when it comes to nutrient feedings, less is more. If I was you in that situation, after my initial mistakes, I wouldn't have upped the nutrient feeding. Next time, look for the leaves, if they start to show deficiencies, put in the same Amount again, if it doesn't fix it, put in a bit more next time.
I have one automatic in my tent aswell, and if I gave it the same treatment as the photos (which are 1 month older), I think it would have been wrecked by now. I'm not using any EC meters tho, just "feel" it.