Cooking watts is the amount of power that heats whatever is inside the microwave.
You have to add to the overhead of everything in the microwave, including the motor that turns the table etc.
From the feature sheet:
16 amp rated.
15 amp x 120 volt = 1800 watt ← max power from nema1-15 outlet
16 amp x 120 volt = 1920 watt ← specification
So your microwave is imo not asking more than specified and allowed according to NEC rules.
From the installation manual:
Dedicated 15 ( or 20) amp circuit for just this unit.
But even with the 15 amp outlet, it doesn’t even come close to what you are allowed to pull.
@lagomorph situation is different.
He either has a unit that surpasses the specs and the allowed power from outlet or the sense measurement is somehow not accurate.
Imo it would be good to somehow confirm the actual usage with a non-sense measuring device.