This is a known problem with Mazda CX-5s years 2017-2021. It happens at around 80-90mph on the highway, especially with strong winds, sideways gusts particular. Here's the Mazda TSB bulletin: static.nhtsa.gov/odi/tsbs/2021/MC-10206007-0001.pdf
Here's where you can buy the rubber parts: www.mazdaswag.com/oem-parts/mazda-pad-kby058769
They are $83 currently.
Hope this helps, and sorry for some pauses, I was out in the parking lot and got distracted by some neighbors.