Thank you for the reply.
What I am seeing is that those fields are not independent. For whatever reason. For example, here is the config of the form
I only have the Mobile Phone field added
However, in the form you can see the Mobile Phone Other field is displayed.
When I remove the Mobile Phone field from the form, the "Other" field is removed as well.
So, I am seeing specific behavior that they are tied in some way in this instance.
Please advise. Happy to open a support ticket if that's best.