Question Squeaks over speed bumps

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My 2006 2WD V6 Highlander has a distinct squeak in the front driver's side wheel area when going over a speed bump. I also can hear a kind of creaky sound when going slow over rough or bumpy surfaces. I have heard these noises almost since the car was new. At first, the service department would spray some lubricant, which seemed to help for a day or two. Then, after a service tech and the service manager rode in the car over some speed bumps, they said it was the strut. At about 15,000 miles, they replaced the left front shock absorber. It still squeaks, but I'm almost afraid to mention it again, because I don't want anything else done until they know exactly what the problem is.

The service department is aware that I live on a dirt road and I ask them to follow the special checklist in the maintenance guide when I go in for maintenance (i.e., tighten chassis bolts). I have driven up and down this road for 28 years, mostly in GM cars, and have never experienced this kind of suspension noise.

My primary concern is safety and whether the suspension is holding up as it should. I have a little less than a year under warranty and would like to get this figured out and corrected before it expires. Has anyone had any experience with a squeaky/creaky suspension?

Thank you in advance for any suggestions or insight!