Which authentication type is mentioned as unsupported by custom connectors?

In the context of Microsoft Power Automate and custom connectors, the authentication types vary in terms of their support. Cookies as an authentication type are not typically used in the context of custom connectors within Power Automate. Custom connectors usually focus on more standardized methods of authentication like Basic authentication, API Key, and OAuth 2.0, which are well-defined approaches to secure API access.

Basic authentication involves sending user credentials encoded as part of the HTTP header, API Key provides a unique key for secure access, and OAuth 2.0 is a widely accepted standard for authorization, allowing applications to access user data without exposing sensitive credentials.

Cookies, on the other hand, are generally used for session management in web applications rather than in API-based authentication methods. They do not fit the model used by Power Automate to interact with APIs, which typically require stateless authentication methods suitable for automated processes. Thus, stating that cookies are unsupported as an authentication method for custom connectors accurately reflects the design and functionality of Power Automate.