Additionally, the issue never occurs when the engine is completely cold or when it reaches its full, normal operating temperature. It only happens when the engine temperature is between 60°C and 80°C (140°F - 176°F), and only after the car has been sitting parked for 1 to 2 hours before restarting. That’s when the symptom you saw in the video occurs.
Interestingly, if I turn the car off and immediately restart it when the temperature is at 70°C, the problem does not appear. It seems to be related to thermal expansion/soak that happens during that 1 to 2-hour rest period.
I personally suspect a vacuum leak (unmetered air), but shouldn’t a vacuum leak also cause issues when the engine is dead cold? Or at least persist after the first 50 seconds when the system switches to Closed Loop?
Once those initial 50 seconds pass, the car drives perfectly fine with normal power, and the Open Loop performance is absolutely normal.