If your Instant Pot sealing ring smells or is stained, soak it in with a mixture of vinegar and water in your sink, a sheet pan, or any other vessel in your kitchen. Let it soak for as long as you want (an hour is great if you can spare the time), wash it with dish soap, and leave it out to dry and air out. You can also fill the whole pot with white vinegar, water, and lemon rind, then run the steam cycle for a few minutes.
Pressure Stinks!