When you are responding to WhatsApp inquiries in Multichannel, some customers might have phone number as their name like screenshot provided.
This happens because they set their name as blank, so Multichannel algorithm decides that the name will be the phone number.
To change the name to something readable, you can edit the name by clicking on customer info and clicking Pencil button
Edit the name, and click the check mark.
The app will show that you have succeeded in changing the name.