Thank you for the very clear example, I am seeing the same problem here. This is currently a known bug, that we are hoping to have a fix for fairly soon:
case=145778
for now I have found a work around, which is adding a comment after the interpolated string, so the function would become:
public void Bar1()
{
string s = $"Hallo\\";
// work around for Visual Assist bug - Console.WriteLine("{folderPath}//");
}
which fixes the problem for me. Can you try this to make sure this works for you as well please.