We don't seem to have a Gentoo bug for this yet.
The docutils dependency in Sphinx is "<dev-python/docutils-0.18". This leads to a rather confusing message when emerging:
(dev-python/docutils-0.18.1:0/0::gentoo, ebuild scheduled for merge) USE="" ABI_X86="(64)" PYTHON_TARGETS="python3_9 -pypy3 -python3_10 -python3_8" conflicts with
<dev-python/docutils-0.18[python_targets_python3_9(-)] required by (dev-python/sphinx-4.3.2-1:0/0::gentoo, binary scheduled for merge) USE="-doc -latex -test" ABI_X86="(64)" PYTHON_TARGETS="python3_9 -pypy3 -python3_10 -python3_8"
This is strictly an informational message from Portage, because it cannot upgrade docutils while Sphinx requires an older docutils. The upstream issue is at URL, and it seems the update on Sphinx's end is slated for 4.4.0.
Upstream explanation 
*** Bug 830131 has been marked as a duplicate of this bug. ***
Here is the actual ticket https://github.com/sphinx-doc/sphinx/issues/9777
Sphinx 4.4.0 with docutils 0.18 was released. https://www.sphinx-doc.org/en/master/changes.html
(In reply to Mike Limansky from comment #4)
> Sphinx 4.4.0 with docutils 0.18 was released.
Where do you see that? It still has <0.18.
This change is currently planned for version 4.5.0 .
Oh, sorry, I missed when they changed target release.
*** Bug 832349 has been marked as a duplicate of this bug. ***
Sadly, this is now targeted for 5.0.0. :(
*** Bug 829252 has been marked as a duplicate of this bug. ***
Upstream PR was merged: https://github.com/sphinx-doc/sphinx/pull/10164