Looks like you had excess salt build up, inhibiting potassium uptake.
Maybe some Calcium problems too. Early stage of Mag def.
The plant seems to be working the problem out on it's own by the looks of the newer growth.
Keeping the plant too dry will cause the salts to build up.
Then, when you do give them a good watering,
the plant gets overwhelmed by the high amount of undissolved salt build up from the partial watering, and goes "wonky" locking stuff out.
I don't think it's a "ph" problem.
Hard to lock potassium out with "ph" alone. (would be below 5.0)
Flush with water, then 1/4 to 1/2 strength nutrient mix.
Your plant is healing up now.
It should be fine, as long as your roots are in good condition.