regarding the extra-bundled-libraries field

Can somebody explain the extra-bundled-libraries field. I find the documentation for it lacking. The official documentation goes into the requirement in naming the libraries and nothing beyond that.
[https://github.com/haskell/cabal/issues/8826](I found this) and it help somewhat. When I use extra-bundled-libraries in my package, it works fine until I tried to install the package using `cabal install` when instead of looking for a static library (.a), it instead looks for a shared library (.so).
So can somebody explain the field more clearly.