I tend to think it is an old wives tale about holes in many plants due to low K+.
Sometimes, yes, it might be true, but I've seen much more evidence with CO2 and NO3 with holes and stunted growth.

If you have good growth and no stunting, and you have a few holes on the lower leaves, then perhaps.

I tend to redo everything and look over things in each area rather than chasing one nutrient.

You have a much higher success rate at fixing the issue this way.
You do not get a chance to isolate and study the deficiency is the trade off, which most folks don't really wanna do anyway.

So do a large water change,. dose things back, add a tad more KNO3, and tweak the CO2 a bit more **slowly**.

Regards,
Tom Barr