For some time, routines have had the ability to be triggered when A switch comes on. It’s right in the regular routine set up now. So “Switch activates home phrase” is no longer needed. Instead, there should be a section “automatically perform…” Near the end of the routine setup wizard where you can select the switch you want to trigger it.
I can’t show you a screenshot, because the current app is not voice navigable, but just edit your routine and you should see the option to start it when a switch comes on.