Hey
@Gary Laser Eyes , there has definitely been nute burn. Most of the damage is radiating from those leaf tips.
OK, so leaves yellowing are fine, but once they start going brown, they are necrotic so should be removed asap.
But while still yellowing, the plant is eating them so only pull when brown take over.
I would say yellowing leaves maybe a couple of possible things going on at moment there.
1 - feeding so heavy its caused damage which is clearly evident.
2 - yellowing leaves are consistent with: hunger, too little light, too much water or die off for nutrients
I suspect you may have overloaded their media with too much food and that is creating other issues if not sorted properly.
Imo Both of these can be rectified quickly by a partial flush: maybe a pots worth of low PH water (6.0) passed through and drained and then half hour later a feed at 50% strength you currently give.
Will also help to alleviate a lock out if the extra nutes are causing probs.
But, just my opinion..
I would ask what your regular PH is and also on what day are they due?
Try not to leave 'leaf' damage to go on so long next time before reaching out.
We've all f'k'd up, missing stuff we should see so we've all been there but some probs you can't afford to wait on.
Good luck.