Can this delay flowering of an auto?

It won't delay it, but more likely impact it in some way, sure... It doesn't have to be perfect to have great results, though. So, don't get me wrong. P-def should have some blueish leaves.. Looks likek boron? But, if you have fluctuating pH, you need to let that balance back out and see if it continues or not... pH fluctuation can cause any and all symptoms. This looks like trace element related, and you likely have that covered in your nutrient mix.. (guaranteed analysis labels, i'm sure you already know this in hydro)... So, i'd lean toward the pH swing... it's not spreading and isolated... All good.. Keep close eye on it. Shit happens fast in water.