DIAGNOSIS: No, it's not normal and it destroys efficiency. The hose isn't fully locked into the unit's rear port, or the inner flapper door is obstructed.
FIX: Disconnect the hose. Check the circular plastic adapter on the unit—ensure the inner flapper moves freely. Align the hose connector's tabs with the adapter's slots and push in firmly until you hear a distinct click. Tug on it to confirm it's secure.
IF THAT DIDN'T WORK: The plastic locking tabs on the hose connector or the unit's adapter might be broken. Inspect for cracks. If broken, you must order the exact LG replacement vent kit part. Tape is a temporary, inefficient fix.
HEADS UP: That leaking air is 120°F+ exhaust. Every bit leaking into your room is heat your AC is working to remove, creating a vicious cycle. A secure connection is critical for basic operation.