It's simple to reproduce: put an effect on an audio clip in a sequence, choose 'render and replace'. The clip is rendered and replaced with the applied audio effects. Then if you 'restore rendered' to get the original back to adjust the effects, the effects that were previously applied are gone.
With video clips, the effects do not disappear from the clip when rendering and replacing, or restoring rendered.
I just noticed this behavior, it wasn't always like this. I've done this many times before. Adding audio effects to hour-hong interviews makes render and replace a necessity.
This is happening on my Windows 11 PC and I reproduced it on my coworker's M1 Max Macbook Pro. v24.6.0 (Build 86)