How to disable Git from automatically identifying and managing embedded git repositories?

When I upgraded Git from 2.24.1.windows.2 to 2.29.2.windows.2, I noticed 
that the embedded git repository is recognized in `git status`, and if I 
use `git add .` will manage the embedded git repository directly as a 
submodule, instead of just ignoring them, which is the behavior I want.

How do I turn this off?

Thanks.