The Problem Details for HTTP APIs RFC provides a unified, machine-readable and standardized recipe for exposing error information out of your HTTP APIs – which is of course beneficial both for the API authors, as well as the integrating parties.
ASP.NET Core has supported problem details since version 2.1, however it was not been uniformly used across all ASP.NET Core components. It was possible to return the Problem Details response manually, or the framework could generate it automatically in several specific cases. Even the official documentation referred to a third-party middleware in order to get a better Problem Details experience.
This is finally changing in .NET 7.