Spaces don't appear out of nowhere, and compilers on CW aren't special either. Based on that, you'll have to make conclusions on your own.

I'd classify that as programmer's mistake, but that's just me. Of course, if you were able to reproduce this: by showing the input, your output, expected output, and the reason it's wrong - then it could become an actual issue. Given that powershell isn't that that popular, it's certainly possible, but there has to be proof and not just words.

Are issues only kata specific? I guess this is more towards codewars in general? If the the in-browser ide acts differently compared to a desktop ide...like adding spaces to a return value that was not added when compiled in vscode, what would that be classified as?

Different node versions, not a kata issue. Sort wasn't always stable in javascript.

Your code not doing what you expect is not a kata issue. Please read this: https://docs.codewars.com/training/troubleshooting/