While working to fix the subwoofer and rear shade, I took apart the the rear 3rd brake light,
and to my surprise, the bulbs doesn't seem to be replaceable. Looks like you'll have to
replace the entire top high mount brake light cover unit.

My brake lights were all fine, but it's a bummer that I have to dish out $160 bucks to fix this light,
should it go out.
https://www.lexusoeparts.com/oem-par...1c0?origin=pla

 

Yes, it is LED-based like the taillights. But it rarely fails and the rear LED lighting gives this car a distinctive and modern look even today.