characters of course. But Windows OS is NOT a case sensitive file system. At least not until Windows 10, build 17107 which then supports the ability to make a directory case sensitive.

My guess is your directory has had case sensitive turned ON. You can check and modify it and turn it off again. That would solve your problem. See "Modify case sensitivity here: https://learn.microsoft.com/en-us/windows/wsl/case-sensitivity