On multiple Kali installations, after an 'apt upgrade', a 'python3-pluggy' package dependency was not met and was concerning 'python3-pytest' package that can't be upgraded because of an overwrite conflict with python-pytest (python2 equivalent).

The following packages have unmet dependencies:
python3-pytest : Depends: python3-pluggy (< 1.0) but 1.0.0-1 is to be installed
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).

If you try the "apt --fix-broken install" command:
Unpacking python3-pytest (6.2.5-3) over (6.0.2-2) ...
dpkg: error processing archive /var/cache/apt/archives/python3-pytest_6.2.5-3_all.deb (--unpack):
 trying to overwrite '/usr/bin/py.test', which is also in package python-pytest 4.6.9-2
dpkg-deb: error: paste subprocess was killed by signal (Broken pipe)
Errors were encountered while processing:
 /var/cache/apt/archives/python3-pytest_6.2.5-3_all.deb

Removing the package requiring this dependency was not possible either because of this dependancy problem.

The only solution was to force the overwrite hoping it is not breaking anything else:
sudo apt-get -o Dpkg::Options::="--force-overwrite" install python3-pytest

The original Kali image(s) were probably a 2020 or a 2019 that was upgraded multiple times up to the latest version.
It was before the migration from python2 to python3 in Kali ... this is probably why we were having this problem.
https://www.kali.org/docs/general-use/python3-transition/