In Rhino 6 & 7, when you click on Tools > PythonScript > Run, a file browser opens, and it has a file type filter so that you can only see python files, which is nice.
In Rhino 8, when you click on Tools > Script > Run, a file browser opens but there is no filter; so, you can see all file types. It’s not a bug, but just not as nice as it could be.