Should we just enable allowCommonHungarianPrefixes? It seems that you don't need to explicitly specify the leading underscore version?

Yes, but CodeFactor still reports "is" and "_is" https://www.codefactor.io/repository/github/powershell/powershell/issues?category=Style&groupId=15

Update: from previous PR https://www.codefactor.io/repository/github/powershell/powershell/pull/8500 - there is CodeFactor reports that "is" and "_is" too.
I do not understand where the problem is :-(

some tools read from master and don't use the configuration files from the PR. I'm just guessing.

It's actually difficult to read the updated config from a PR as the json you get back is just the diff of the file and not the complete file. This is why for @PoshChan I always look in master rather than trying to generate the resulting config file from master + diff.

@TravisEz13 There is really a problem. As @SteveL-MSFT mentioned above allowCommonHungarianPrefixes enabled "is" by default - I found this in source code too. But CodeFactor continues to report "is". We can see this in previous @daxian-dbw PR #8500 - it seems CodeFactor read config from commit - and then in master too.

@SteveL-MSFT @TravisEz13 @daxian-dbw

I received a response from the CodeFactor support:

Thank you for reaching out.
CodeFactor supports Settings.StyleCop file as config, but not stylecop.json (it will be supported once https://github.com/DotNetAnalyzers/StyleCopAnalyzers/releases is out of RC).
So, you can still configure StyleCop to do what allowCommonHungarianPrefixes proposes by modifying Settings.StyleCop file (e.g. https://stackoverflow.com/a/45606734)
Please let me know if I was able to address your inquiry or if you need anything else.
Thank you,
Sandra Jones
Your CodeFactor.io team
Track CodeFactor.io feature announcements on Twitter https://twitter.com/CodeFactor_io

So I reverted previous commit and change Settings.StyleCop as recommended. You can see that now CodeFactor reports "2253 issues fixed."

We could move stylecop.json to Tools folder and use Settings.StyleCop until CodeFactor get new StyleCopAnalyzers version.