Apparently there's a new function with Android 13 for muting the phone, and unfortunately it's tied to the watch and also to Google home devices. There is no way to unconnect these.
If either of the Google home devices such as Google home mini or Google home Max or the regular Google home, silence devices it will silence your watch and your phone. And actually if you put mute on the phone or the watch it will mute all others. These should not be forced to be connected. Right now there is no option to disconnect them. There are times for example you want your watch to sound but not your phone. You can turn down the volume on the phone but on the watch the main button is now mute when you turn off the sound. This affects all other devices.