Currently, when you have a repository with some permissions set up and create a new fork from it, the new repository will not have the same permissions. I'm not sure if this is the intended behavior or just not implemented, but it would be nice to be able to copy permissions from the parent repository, ideally automatically.
The use case here is that there are main repositories to which developers have access and they create forks for their own development. It makes sense for all developers with access to the main repositories to also have access to the developer repositories. It's frustrating that when you create a pull request, the reviewer does not have access to the source repository and can't do manual testing/merge.
If you see a use case where it's not a good idea to automatically copy the permissions, perhaps it could be an option on the permissions page.