Problem with plant, have a pic of a leaf that fallen off

Hey,

So around 1.5 weeks ago I was told that my plant is having a root bound issue and due to that It's nutrients are becoming unavailble. I was told to water with no nutes for the next 3 times so the soil will clean out before going back to giving nutes. Now, my leaf problem is mixed, i'm not sure if its a Pottasium problem, a nut burn problem, both of them or even something else such as pH fluctations (new pH tester might not be reliable). I have added a photo of one of the leaves that shows the symptoms, I have around 10 leafs like this on the plant and it's mostly on the bottom-middle of the plant going upwards.

Would really appreciate the help! If needing more pics please tell

If it is rootbound, transplant...and it looks like a def of nutes feed them after you transplant!

thanks, wasn't sure if its a burn or a def , since my the color of water after watering was darker than the water with nutes I gave.

I have transplanted her to a larger pot, she has been getting roots accelerator without nutes to clean abit the soil. If it's a defiecy she will start getting nutes again tomorrow, made sure so far that ain't too much nutes in the soil to have her suffer a nute lockout (i'm mostly afraid if this since it could be the source of the defiecy).

Not a burn!Once flushed with 3 times water/pot size,there should be no lockout you can start to feed nutes! She will be green in no time but the ones damaged will still not look great but you will notice a difference soon! Good luck!