It's fine. It might be gross or sickly sweet, depending on how long it's been fermenting.

Auto-brewery syndrome is super rare. It's caused by conditions that allow brewing yeast (and other fermenting microbes) to live/thrive in your gut when they shouldn't. Nutritional yeast is also living brewing yeast, though it's dormant and not actively fermenting when eaten. You will get a bunch of B complex vitamins from the yeast!

But beware, my friends used to call green beer 'fartzens,' after the original Hefefartzen that we drank way too early.