It being there isn’t going to impact on anything, as the OP said.
“If you’ve used Avast for a long time and have upgraded it to the most current version, you may have noticed avastSS.scr in your Windows directory.”
I too have only updated from the UI on this win10 home 64bit laptop.

Program updates from the UI are going to be adding/modifying elements and not so much cleaning up. We can only hazard a guess if an uninstall and clean install would have removed it or not.