I noticed a few weeks back then when I turned corners it sounded like something rolling around. I figured it was something in the trunk of the door storage compartments and didn't think much of it. Until it got much worse.
I isolated to something in the headliner. When I tap the roof above the passenger visor, it sounds like a bunch of loose change is up there.
My worry is rodents brought some acorns or something up there.
Any ideas? It's a 2018 Rav 4 and I'm a little over my 2nd year in the lease. I'm assuming the dealer won't diagnose this for free since they need to take headliner off most likely, right?
Do you have a sunroof? Can't tell from the trim.... If so, I'd open it and see if anything is loose and rolling in the front cavity there. Possibly loose pop-up wind deflector.
Secondly, when you tap on the roof, is your visor in its socket? This is strange, but one of the rattles I have / had with my 2017 XLE is the sliding cover of the visor mirror, rattling against the visor itself. This is curable by felt tape in strategic places....
Failing that, I'd go with Fibber2's suggestion. This is still non-destructive / reversible. Possibly, when you drop the senter console, fish a magnet on an antenna stick there, just in case.
Finally, I'd also try to remove the passenger grab handle - again to look inside.
I would also check if any of the headliner retainers throughout the car are not broken / fell through.