Well it doesn’t matter if she pronounces it different than most people, she gets to decide how she wants it pronounced, so if you’re saying it different when talking about her specifically, then it’s wrong.
My brother has a similar situation. His name is Norwegian, and technically it’s pronounced much different than how it’s spelled, and it’s a girls name. However he just says it how it’s spelled, so it’s technically incorrect. He still prefers it to technically pronounced “wrong”.
Point is, the person with the name gets to decide, and Kamala says it’s Kah-muh-la, so that’s what it is. Anyone pronouncing it differently (on purpose or on accident) technically has it wrong.