Not really in this case, potassium chloride is used for potassium depletion via intravenous drip all the time. The quantities in a jab is so small it would have no effect.

The Pfizer doc lists it as 1 mmol (39 mg) per dose, it really would not cause any increase in the body, virtually potassium free.

Though I know this goes around on social media, but I would bet someone knew that potassium in high levels can cause heart problems, but they did not realise the scale required or any of the actual numbers or science but still decided that it was a risk and bad.