Why does Siri’s voice keep changing for some apps

My Siri voice selection is American voice three. Every so often, maybe every two days, the voice response I get from the Apple weather app is something else entirely. In order to remedy this, I need to restart the phone. This has been going on for a year. This is not acceptable. Does anyone know what’s causing this? Or why it would not have been fixed by now? It’s also annoying that, seemingly at these same times when I ask for the weather forecast I will get something like, “It appears to be cloudy outside.” With no other details. Really frustrating.