The issue is that you need =80 instead of 80 after --line-length for version 1.38.1 and above:
--line-length=80

The issue is that you need =80 instead of 80 after --line-length for version 1.38.1 and above:
--line-length=80

Hopefully the answer for a more recent VSCode and Black helps:
With VsCode Insiders (1.83.0-insider) and Black installed from extensions (v2023.4.1), installed from extensions (https://marketplace.visualstudio.com/items?itemName=ms-python.black-formatter)
I had to add -l or --line-length and 80 as separate items to File->Preferences->Settings->[type]black->Black-formatter: Args->Add item.
In user settings json (Ctrl + Shift + P --> Open User Settings) I have:
"black-formatter.args": ["--line-length", "80"]
If this doesn't work, there's useful information in the Output Window (you can select Black Formatter) to see the logs from Black.
Videos
For all three formatters, the max line length can be increased with additional arguments passed in from settings, i.e.:
- autopep8 args:
--max-line-length=120 - black args:
--line-length=120 - yapf args:
--style={based_on_style: google, column_limit: 120, indent_width: 4}
Hope that helps someone in the future!

@tkazik answered his own question correctly, however, I thought it would be helpful to include some references:
VSCode documentation on using Python formatters:
https://code.visualstudio.com/docs/python/editing#_formatting
autopep8 command line options:
https://pypi.org/project/autopep8/#usage
- Note that there is also an option to point the formatter to a global config file
- Additionally, if you have a local or global config file in the expected location, these preferences will be used automatically by the formatter in VSCode (https://pypi.org/project/autopep8/#configuration)
black command line options:
https://black.readthedocs.io/en/stable/usage_and_configuration/the_basics.html#command-line-options
yapf command line options:
https://github.com/google/yapf#usage