After the latest update of PHP Intelephense that I get today, the intelephense keep showing an error for an undefined symbol for my route (and other class too), there is no
You don't need to downgrade you can:
Either disable undefined symbol diagnostics in the settings -- "intelephense.diagnostics.undefinedSymbols": false .
Or use an ide helper that adds stubs for laravel facades. See https://github.com/barryvdh/laravel-ide-helper