Hey guys I'm puzzled i took one picture of a ...

Hey there Cedji, doesnt look like pH fluctuations at all but it does look like pretty standard N deficiency along with either calcium or pests. So you can tell it's N deficiency because older/oldest leafs are affected first, yellowing basically evenly. You also look like there's a calcium deficiency, those are the small rust spots on the leafs , but they could very well be from pests aswell, just check the underside of the leafs to see if there's any tiny microscoping black dots or any other signs of pests (i'm probably just being paranoid but it doesnt hurt to check) Maybe next run what i do recommend is to use some cal mag, because these kinds of genetics basically always need extra calmag , and next time feed your auto some bloom nutrients around week 3/4 and keep some kind N input going through flower if you want these plants to reach their full potential. Hope this helps ! 🚀