What is ls `/immich/library/library` and why is it empty?

At first, I had a heart attack thinking somehow my phots went away, but they are there on the web, and I can see them in

/immich/library/upload

/immich/library/upload

So what is this folder?
Why is it created? Or is it a rest of obsolete path?

What is ls `/immich/library/library` and why is it empty? - Immich