4 days without water

That just the plant taping into her energy storage just keep up with proper feed

I don't know what FFOH is, seem a lot of ppl using FFOF fox farm ocean forest. cant say much based off the medium but it looks to be soil based. Your PH is also on point for soil. 6.3 I'd try and keep it aorund 6.5-6.8 though if this was me. It looks to me you where showing some deficiencies in week 4 and it progressed into week 5 and now 7. week 6 was skipped??? The fertilizer you used in week 4 was not listed in the diary feed intake but was in the description and the concentration was not reflected in the EC that you are feeding them. every week has been .3ec, this does not make sense. this is the recommended feeding dose for the fertilizer line your using. I don't see that your using the grow just the bloom with some calmg. https://ilgm.com/products/marijuana-fertilizer-set I think your main issue was the plants needed more food in week 4 and it was to little to late and this is the outcome. You want to stabilize your feeding regime and manage the EC better as well as watering. check you feeding solutions PH and EC after mixing. given that it is soil it will help buffer things for you but also hold onto a lot of the nutrient you put into it. flushing soil can be bad if its compacted as all the excess water will drown the roots if it does not drain well. I don't see any N tox as suggested below, but do see issues with CaMg. Your calmg supplement will also have some N in it. Try finding out your solutions EC when your feeding once a week and work from there. Good Luck!

@GrowingGrannie disagree would be a better word than argue. You are entitled to your opinions.

Going to argue a bit with FreeCain here... if this had been the result of "earlier issues" you would have seen some damage before you left for your 4 days. I'm also a bit skeptical of his/her knowledge since he doesn't even have one diary which we can look at to see how successful a grower s/he is... Please... This is CLASSIC nitrogen toxicity and if not corrected will only get worse... it starts at the lower leaves and then moves upward to consume the whole plant... Please read what I've said below...

Routine feeding is the way to go. Just showing the previous damage on the leaves from your earlier issues. Best of luck the rest of the grow.