Deffo sounds like a pulley (bearing) in the aux system, which one should be apparent after belt is removed, or ( at your own risk) you could improvise with a screwdriver stethoscope and check each driven unit, water pump, idler, AC etc.
So…..did you ever get to what was the source of your rattling noise you reported back in Dec 2021,
https://www.lexusownersclub.co.uk/forum/topic/131180-grinding-noise-under-the-car-please-help/#comment-1212692
or is this the same issue and this is how it sounds today as you never reported an outcome back then?