How to use Windows user name in WSL2 shell script?

Question

I have tried this:

WIN_USER=`powershell.exe '$env:UserName'`
WIN_HOME=/mnt/c/Users/$WIN_USER/
echo $WIN_USER
echo $WIN_HOME
ls $WIN_HOME     

and I cannot figure why I have this ouput:

pierr
/mnt/c/Users/pierr
ls: cannot access '/mnt/c/Users/pierr'$'\r''/': No such file or directory