Bumper covers change all the time for a mid generation refresh. They could absolutely remove the honeycomb inserts or completely change the bumper covers with or without affecting the base hatch.

“On most cars if you buy them new from a dealer if you change your own oil it voids the warranty”

This is absolutely not true. I’ve done every oil change on all my cars purchased new for the last 26 years and have never been refused warranty service.