N62 4.8i unusual top end engine rattle/sound

[celicasaur]

Hi folks, first time poster here, I hope you're all well

My E70 4.8i randomly starting making this sound, seemingly from the top end and I'm quite confused as to how I should go about diagnosing and solving the issue. It's the week before Christmas, so I'm mindful that I won't even be able to get a look in at a workshop any time soon.

https://www.youtube.com/shorts/UEWTUdgdj-g

Any thoughts?

FYI I replaced the water pump this weekend, to no avail (old pump was fine) and I've tried clicking the A/C on/off to see if. it alters the sound, but no joy there either.