You may wish to post in the car section, this is general discussion and generally has no discussion.
The short answer is that nothing is behind the pillar covers. They screw at the bottom and are overlapped at the top by the plastic trim. Any number of these can be loose, need tightening or have worn plastic allowing movement. The corner Y-trim actually wraps around it with a small tab, often crumbled and missing.
Fairly easy to remove for a look, add some sponge rubber that will compress and refit.
