@George makes a point with potassium deficiency. While overwatering can cause all sorts of strange deficiencies to show up, there’s usually tell-tale leaf droop—and potassium usually isn’t the first deficiency to show up from overwatering.
The most common causes of potassium deficiency, assuming you’re using some nutrients, are lack of aeration/drainage causing root issues and high pH due to bad pH calibration or not using a pH meter at all.
More details would help, such as what sort of soil you’re using, how much & how frequently you’re watering, what nutrients (if any) you’re using and how much/often, pH of your water/nutrient solution, etc.