Creaking noise from front end over speed bumps - control arm bushings or something else?

Hey all. This summer, I traded in my trusty Toyota iQ (gonna miss that little guy) for a JDM imported '06 Prius for the extra cargo space and better fuel economy. I figured it had potential to be a diamond in the rough at just 75k kms.

I've had a fair amount of work done on it already — new HV battery, tires, spark plugs, Bluetooth audio (did those last two myself), cabin air filter, and a full check over at the local express auto service centre.

But this issue has been annoying me. It's so far eluded diagnosis at that auto centre, and based on my research at home. I've taken it in to be seen twice, and both times they said not only could they not find the issue, but they thought my suspension is in great shape! To be fair to them, the issue doesn't impact handling at all.

Here's the symptom: in weather under 18-20C, the front end makes this scraping/creaking noise when going over speed bumps over about 25km/h. The noise gets quieter and less frequent after about 10 minutes of driving, but doesn't fully go away.

I found threads here on this forum that indicated the issue may be bushings on either the sway bar, or the lower control arms, and that the fix was to hit them with some lubricant. Well, half a can of silicone grease spray later, I can say it wasn't that easy.

I am technically inclined, but my expertise is more in computers than cars. I think if it's a simple job — maybe replacing those control arms — I should be able to do it myself.

Curious if anyone else recognizes this issue, or knows how to locate the part that's causing it?