Your frame rate reading an exact 30 FPS makes me almost positive that you are using motion reprojection?
If you are using motion reprojection, you cannot look at the CPU frame times in dev mode (and therefore cannot look at the “limited by” either), because they include the frame throttling sleep necessary to lock your frame rate to do motion reprojection.
Same story for those artificially limiting frame rate via their GPU driver.
Use OpenXR Toolkit overlay instead, it’s the only tool that can have proper measurements in VR (as long as you are not using its Turbo Mode).
See my very detailed post here to someone who had exactly the same symptoms (not calling it “issue” since it’s not an issue).