At my employer, Python is not our primary language; the main system was built in Perl and is now a Perl/PHP hybrid. The surrounding systems have been built/replaced with PHP, but the core code is resistant to change. Management doesn't want to mess with the part where the actual money flows in.
For seamless session handling—local memcached on dev machines, but shared storage in production—we have memcache-dynamo. It started life in Perl. I rewrote it in Python, as part of the quest to replace all Perl with something more popular in modern times. (I figured async/await syntax would be easier for future developers than React-PHP.) It's been working fine on Ubuntu 18.04 for some time, but then I wanted to update to Ubuntu 20.04.
It quickly turned irritating. The Python 3.6 dependencies didn't work on 3.8. It turns out that the updated dependencies for 3.8 don't work on 3.6, either. I guess this explains why pipenv is so insistent that "requires 3.6" means "exactly 3.6".
Python 3 isn't just a version with some backward-incompatible changes; it's fundamentally a new culture with new values. And honestly, that probably means less Python in my future. I don't want to promote another language into the main systems, and Python no longer seems to be suitable for fire-and-forget background services.
(In the end, I wrote a new layer on our installer that checks the Python version, then copies e.g. Pipfile-3.8 and Pipfile.lock-3.8 into their standard location before starting pipenv. It's a horrible mess and I hate it so much. Please, don't start a Python 3 transition every year!)