I'm sorry, but the knowledge sources provided do not mention an oauth_provider field in the context of Ory Kratos. There is information about configuring OAuth2 and OIDC providers, and about fields like provider and id in social sign-in and identity import configurations, but nothing specifically about an oauth_provider field. If you have a specific context or configuration snippet where you see this field, please provide more details so I can help clarify using the available documentation.