Nutrition problems?

I am having a problem with one of my plants and would appreciate some help.
I’m growing strawberry Kush plants (3).
And one of them is having problems with some leaves.
Two near the top, two in the middle and two on the bottom.
I’ve grown these many times and never had a problem till now.
They are growing in 5 gallon containers of Fox Farm Ocean forest soil for 8 weeks.
I pruned them about three weeks ago. Started noticing the leaves changing around 2 weeks ago.
The water pH is 6.5
Started feeding bench nutrients about four weeks ago.
Using LED lights.
I’m hoping that someone can identify the problem by looking at the leaves.
Not having this problem with the other ones. A couple of the lower leaves on the other plants became yellow but I think that’s normal for the age.
I would appreciate any advice on how to fix this.

What are you using to measure pH?

I use an Apera PH 60.
It’s supposed to be accurate.
Do you think this is a PH issue?