Conversion of docstring (probably but wrongly) triggers the reStructuredText formatter

I maintain the pyvinecopulib package and my docstrings are not properly converted by sphinx. Essentially, doing import pyvinecopulib as pv and help(pv.Bicop.loglik), I get:

help(pv.Bicop.loglik):
 |  loglik(...)
 |      loglik(self: pyvinecopulib.Bicop, u: numpy.ndarray[float64[m, n]] = array([], shape=(0, 2), dtype=float64)) -> float

However, the doc generated by sphinx appears as loglik(self, u, n]] = array[, dtype]). I have plenty of similar examples, but essentially, both the argument type and default value does not seem to work properly.

Steps to reproduce the behavior:

git clone --recursive https://github.com/vinecopulib/pyvinecopulib.git
cd pyvinecopulib
git checkout dev
pip install .
cd docs
make html

Then open _build/html/_generate/pyvinecopulib.Bicop.html.

The docstring appears correctly:

But sphinx's generated documentation does not:

Is it possible that conversion of the docstring (probably but wrongly) triggers the reStructuredText formatter somewhere? Or any idea what could be the issue?

Note that the docstrings were automatically generated by pybind11 and that I used

pv.doc() = R"pbdoc(
  The pyvinecopulib package
  -------------------------

  .. currentmodule:: pyvinecopulib

  .. autosummary::
     :toctree: _generate

     BicopFamily
     bicop_families
     Bicop
     FitControlsBicop
     Vinecop
     FitControlsVinecop
     CVineStructure
     DVineStructure
     RVineStructure
  )pbdoc";

in my main.cpp file (where pv is the name of the module).

Also, my conf.py has

import sphinx_rtd_theme
extensions = [
    'sphinx.ext.autodoc',
    'sphinx.ext.intersphinx',
    'sphinx.ext.autosummary',
    'sphinx.ext.napoleon',
    "sphinx_rtd_theme"
]

autosummary_generate = True

to generate automatically what is needed. I have replicated the issue on 2 different versions of Ubuntu and one Mint install.

Reproduce the issue in the pyvinecopulib documentation setup with sphinx.ext.autodoc, autosummary, and napoleon by running the listed install and make html steps. Compare the generated _build/html/_generate/pyvinecopulib.Bicop.html with help(pv.Bicop.loglik) and determine why the pybind11-generated argument types and defaults are altered; done when the generated documentation preserves them.