XC60, Odd noise from rear passenger side

The wife’s xc60 mk1.5 has developed an odd squeaking noise from the rear passenger side.

Noise tends to come once the car gets over 30 and then is constantly there. It will only go when the car is braking. The noise disappeared for a day or two due to how wet it was.

Car has been into local garage a few times and they can’t see anything on the underside. They did think it was the heat shield, so tightened it up. But problem persists.


Video of said sound https://youtu.be/4ozZ8vkJCCo