The VVTi is mounted to the Camshaft, in the front. If the small "gasket" that is a rubber seal happens to get old it will leak oil into the valve cover body. The issue is that the VCT solenoid will lose pressure and that will cause the VVTi to not move the timing control gear into the "lock" causing a rattle. The gasket / rubber part is a small figure 8 looking seal that in inside the upper valve cover (head cover).

The car had this rattle when I bought the car. After the Head Gasket had an issue in Nov 2022 I took the engine apart to look at some things that I find strange. The VCT Cam Oil Hole gasket is hard and I assume its just old. Looking on the internet it seems to be something Lexus may have known.

The other item related to this is the hi pressure oil line that feeds the VCT hole / gasket. If you remove the oil line / tube that runs from the lower block up to the valve cover, it has a small screen filter. It may be clogged on an older car that a previous owner put some kind of junk in the oil to maybe thicken it for many different reasons. Could have been Lusas oil additives or something like that to calm the noise or maybe try to stop the rattle from old rocker arms, you just cant say. The filter needs to be cleaned.