DIAGNOSIS The silicone or rubber sealing gasket absorbs odors and can transfer them to bland foods like rice. It needs a deep clean or replacement.
FIX Remove the ring from its groove in the lid. Wash it in hot, soapy water. To deodorize, boil it for 10 minutes in a pot of water with a tablespoon of baking soda or white vinegar. Let it air dry completely before reinserting.
IF THAT DIDN'T WORK If the smell persists or the ring is cracked, stiff, or permanently stained, you need a new one. This is a consumable part. Search online for "IMUSA pressure cooker gasket" or "sealing ring" matching your model (e.g., 7 qt). They are inexpensive and crucial for safety.
HEADS UP Always remove, clean, and dry the sealing ring after every use. Storing the lid with the damp ring in place is the main cause of mildew and permanent odors.