Craft 3 auto-creates sub-folders in assets. How can I prevent this? I use Google storage for photos. The Google storage volume is mapped to a bucket's subfolder.



Unfortunately these appear as subfolders in assets, along with a set of repeated folder structure. I did not create these. 



Any way to prevent CraftCMS from creating them? What is the cause they get created?

P.S. Is it possible that they are the remainder of subfolders which I created on the filesystem before setting up the assets to use google storage? I did delete the local storage assets volume between creating the google storage one. But, the local storage did have the ahtletes/photos in the local assets folder. 

At this time, the local assets folder does not have the athletes/photos subfolder.

I am trying to understand what action or process creates these folders?
My guess would be your Asset Indexes are out of sync.

If you go to Settings->Utilities in the Control Panel, there is one that says "Update Asset Indexes".  Click it, let it run and you might be prompted to resolve some out-of-sync indexes.  Once you do that, it should work normally.