Ph or something else?

I have few plants whos bottom leafs look like this. Is it 100% ph problem or could it be smth else?

Could be other stuff.

Could be over feeding. Could be nute lock due to ph. Ph should be in between 6 and 7 in general from my experience.

Flush
Correct ph 6-7
Get correct nutes none if soil is nutrified already
Light distance
Jobs a gudn