This is a common problem. The cause is that the rubber seal on the inside of the lid is very good at absorbing odors. So, before you know it, your Instant Pot lid can start to stink from garlic or whatever else you've been cooking. My best tip to keep the lid from stinking is to wash it after every use and then store the lid upside down on top of the Instant Pot base. By storing the lid upside down, you'll expose that underside and the seal to the air which will keep it from stinking.