Problem with Subdivision Surface after Bevel Creating a very simple figure out of plane with Bevel modifier following by Subdivision Surface resulted in weird geometry.
Steps how to reproduce the problem:

I've used a mesh plane,
squished z-axis and applied scale,
then added 4 loop cuts,
then moved middle part with G or move tool,
afterwards added modifiers
and used shade smooth.

Normals weren't changed, all geometry is same as before, no n-gons were created. Why this might happen?
Simple plane with 4 loop cuts

Bevel settings

Subdiv settings

normals
It looks like you've only applied SubSurf to one set of faces. Try applying the solidify modifier, if you can, then bevel your edges and apply the SubSurf.