Today, I sent a text to someone who I had not put in my contacts yet. I told Siri, "Send message to and then I said the phone number with area code. A few seconds later, I got a notification that the message failed to send. However, about an hour or so later, I received a text response from the person that notification said didn't send. Very interesting.
I can confirm that I had the very same issue, but it occurred when I would ask the HomePod to send a text, but to someone I had in my contacts.
I had reported this to Apple and haven't tried it again since the recent update. Hopefully this recent update corrected this issue.
Doing well. My issue is that when I use siri, VO starts talking and affects my text or question. Hope iOS 13.4 fix this but probably not.