Can someone help me understand this attack?

He basically SWAPS 0.000000001 BNB for some otkens, and then somehow swaps more tokens that he got for > 1.71 BNB.

I would like to understand where the vulnerability is (I assume in the token, obviously not in panckaeswap), how to prevent it, and how the attacker is exploting it.

Thank you!

I don't know how. but thats impressive.