Why can’t my 4 year old chew with her mouth closed!?

I’m not even kidding (I counted...) I said “chew with your mouth closed” 45 TIMES AT BREAKFAST THIS AM. Not to mention it takes her 30 minutes to nibble about 1/4 of her pancake. I’m not exaggerating, this is all accurate. 30 minutes for 1/4 of her pancake! And repeating myself 45 TIMES! Is this normal!???!!!!?? I’m going to lose my mind. She’s 4! She should be able to listen to something so basic.