Nute lock out or natural?

Where are you testing your soil PH? Slurry or run off? I would just lower your input water PH. If you are growing organic like this your input water should be between 6.5 and 6.8 to support the biology in the soil. I would use a compost tea or recharge to reactivate

Hello to lower your ph in soil you have a best chance at adding some decomposing manure mixing it in at the top that can bring it down organically over time this to me looks like your spot on in your guess. You can use peat too to lower the ph. Yes it can be normal looks like she has a bit too much nitrogen in her for this stage. I would advise flushing as much as you can without over watering which can be hard give her a few days flush and see how she looks in a few days it may help with your ph too but the discolouration of leaves could also be down to the ph that could also discolour your leaves though this wont really effect growth if you can sort it in time before it gets more of a problem :) my 2 best guesses :) just my opionion I could be wrong but anyway she looks like a nice plant keep up the great work :) 👊