Unexpected header rendered for custom Napoleon section alias

Describe the bug

For a custom Napoleon section alias we would expect the original header label to be rendered, but it is the alias label that is rendered instead.

How to Reproduce

conf.py:

project = "Thing"

extensions = (
    "sphinx.ext.autodoc",
    "sphinx.ext.autosummary",
    "sphinx.ext.napoleon",
)

autodoc_default_options = {
    "members": True,
}

autosummary_generate = True

HW_PROPS = "Hardware Properties"
napoleon_custom_sections = (
    (HW_PROPS, "params_style"),
    ("HwProps", HW_PROPS),
)

index.rst

API
===

.. autosummary::
    :toctree: autosummary
    :recursive:

    thing

thing.py

class Thing:
    """The thing

    HwProps:
        color (str): The color of the thing.
    """

We would expect the section header in the generated HTML documentation to be the original label Hardware Properties, but instead it is the alias label HwProps.

Environment Information

Platform:              linux; (Linux-6.1.0-25-amd64-x86_64-with-glibc2.36)
Python version:        3.12.2 (main, Mar 11 2024, 16:50:09) [GCC 12.2.0])
Python implementation: CPython
Sphinx version:        8.0.2
Docutils version:      0.21.2
Jinja2 version:        3.1.4
Pygments version:      2.18.0

Sphinx extensions

• sphinx.ext.autodoc
• sphinx.ext.autosummary
• sphinx.ext.napoleon

Reproduce the issue with conf.py, index.rst, and thing.py using the listed Sphinx extensions, then inspect the generated HTML for the Napoleon section heading. Trace how napoleon_custom_sections maps the HwProps alias to Hardware Properties, and consider the expected original-label behavior done when the generated heading shows Hardware Properties while the documented parameter content remains intact.