Here's the current bus map for Lausanne: https://www.t-l.ch/app/uploads/2023/12/plan_schematique_r24.pdf
Route 52 used to run between Echallens and Beaulieu, Route 51 between Cheseaux and Prilly, route 50 between Romanel-sur-Lausanne and Prilly. These three lines were decomissioned two years ago. I personally work for the Lausanne transport authority.