So I have a 2017 SR and it developed a buzz behind the glove box related to engine speed, started about 1900rpm and ceases about 2500rpm. Annoying to say the least, dealer checked it out and said it was a heater tube clip that causes the buzz. Anyway Toyota accepted to fix under warranty, sounds like a fairly common thing as there was another guy with same problem in at the same time.
Booked it in for warranty fix, they needed it for the whole day as they need to remove the dash to fix. I picked it up and the service guy said 'see how it goes, they just put some tape on the tube and re-used the existing clip but sometimes we need to order a new clip from Japan'. Needless to say 2km down the road the buzz returns. Called them and they said they'll order the part and then book in for another day to repair.
So my tip is if your Gen 8 gets the same rattle insist they get the replacement part so you don't have to drop it off and drive a courtesy car twice....