while drinking my beardie will submerge her entire head under water for up to 45 seconds ish. she will keep opening her mouth the same as when she would drink above water. when done she will puff up and stick her head up into the air, use her 2nd eye lids to clear her eyes, shoot some water out of her nose and lick her lips.
she has been drinking this way for over a year but i thought id ask if others do this too
It's not uncommon for them to drink with their head submerged like that. It can cause issues if they wind up inhaling the water. I prefer to offer water in smaller batches by dripping on their nose. They tend to tilt their head downward and lick it that way. There is less chance for them to inhale the water when they aren't drinking so much at once.
If she's used to it and it hasn't posed a problem, she'll probably be fine. I know the behavior you're describing and it is fairly common when they are in water and want a drink.