After talking with a branch manager at my daughter's bank, I learned that it might be a recurring charge via Google Play Store, from my daughter's Android cell phone. The manager showed me how to access the subscriptions that are active on the phone, and the culprit was found!
In this case it was a subscription to AMC+, that was subscribed to by my daughter. We pay for this already via our cable provider, and my daughter may have thought it was cool to watch a show on her phone. Probably she clicked the link, and gave her debit card number when prompted, thinking that it was connected to our cable. Of course, it was not.
But she doesn't remember doing it, and $9.48 comes out every month. I was able to cancel the subscription on her phone (with a few others!) Now we'll see if the charge recurs on August 29. Hopefully the problem is solved. Hopefully this helps others.