The .NET team has released a set of rules for ASP.NET Core developers to help improve the quality of their code. These rules address various issues such as controller bloat, endpoint performance, metadata coherence and API documentation, model definition and validation. The rules aim to help developers avoid common pitfalls like adding unnecessary actions to controllers, using inefficient HTTP clients, and neglecting proper metadata and validation in models. By implementing these rules, developers can create more maintainable, efficient, and secure ASP.NET Web Apps.