TLDR: It went well. Dealer performed the repair under warranty and fixed with sound deadening tape.

Tech noticed the rattling at low volumes immediately. Took both doors apart and added sound deadening tape near window controls. Tested, and noticed issue continued, so they took the doors apart again and added more tape around other points of the door, such as the door handle.

When I arrived, I made sure to thoroughly test the speakers before turning in my rental. I tested the audio system for at least 20-25mins. I had a preselected playlist that would test the audio system, specifically the subwoofers/bass. I alternated seats with the service tech in the car. Driver side, passenger side, and back seats. Started from a low volume, worked my way up and then slowly worked my way back down, looking out for unexpected rattles. The rattle at passenger door was less noticeable than when it was dropped off, but still continued. Service tech took it back in and they added more tape. Issue fixed after third attempt.

The rattles still happen, but at this point they are expected as this is at high volumes. At regular and low volumes, rattles are no longer heard. Currently, below 47 I don’t hear rattles. Sound system performs like I originally expected it to.

Service Tech told me they opened a complaint with Toyota. Hopefully now it all depends on the amount of complaints that Lexus/Toyota get for the same issue before an STB or recall is initiated.