Speaker always ON by default when calling with Siri in iOS 13.1? Here's a workaround fix

Yes it is definitely broken, here is a workaround that mostly worked for me:

1. Go to Settings > Assessibility > Touch > Call Audio Routing

There are 3 default choices: "Automatic", "Bluetooth Headset" or "Speaker"

2. Choose "Bluetooth Headset". NOT the default "Automatic" - which is broken in iOS13.1

NOTE: I do not use much less own a Bluetooth headset. But it mostly fixes the problem.

If it's like my iPhone 11 Pro, it will be on "Automatic" by default - which always turns speaker when using Siri to make a call. But I just tested it after switching the setting to "Bluetooth Headset"., and when I asked Siri to call a number, she responded that she is calling that number using the speaker. But... the speaker was OFF. Let that sink in - this a very broken iOS feature.

So, it goes to speaker when it is set to the default "Automatic", and doesn't when it is changed to "Bluetooth headset".