DIAGNOSIS That's not normal pressure release—that's a leak. The seal is compromised, usually because the sealing ring is dirty, damaged, or not seated properly. It means pressure isn't building correctly inside and your cooking times will be off.
FIX 1) Turn the heat off immediately and let the pot depressurize naturally. 2) Once safe and cool, open it and inspect the silicone sealing ring. Remove it, wash it thoroughly in warm soapy water, and check for any tears, nicks, or permanent deformities. 3) Dry it and the channel it sits in completely. 4) Re-seat the ring meticulously, ensuring it's snug in its groove all the way around with no twists.
IF THAT DIDN'T WORK The leak might be coming from the pressure release valve. Remove the valve assembly (usually it just pulls or unscrews) and clean any tiny food particles that might be preventing its weighted cap or silicone seal from sitting flat.
HEADS UP A steady, gentle rocking or jiggling of the weighted pressure regulator is normal. A loud, angry hiss or jet of steam from the lid seam is not. Always address a bad seal before continuing to cook.