Looking at the Local codebase, that tempfile.ps1 is a powershell script file that Local creates when it determines that a newer version of Microsoft Visual C++ Redistributable is required.
This is a collection of shared libraries that comes from Microsoft:
I’m guessing that Avast is flagging this file as a threat because it’s a script that’s downloading and installing .exe files – in this case, files like vc_redist.x86.exe and vc_redist.x64.exe.
If you allow Avast to keep blocking that file from running, you’ll want to manually install the latest versions of the Microsoft Visual C++ Redistributable so that the latest libraries for Windows are available for Local to use.