Oyster Sauce. Good or Bad?

Hi mummies, is oyster sauce really not healthy? My mum has been coming to my hse to help with baby and cook dinner. She likes to use oyster sauce to cook veggie and sometimes meat. I have a toddler as well and recently just started her to eat rice. So she is eating my mum’s cooked food as well. So ai’m abit concern on using oyster sauce.