Gatsby 2.5.0 introduces significant enhancements to the schema customization API initially released in version 2.2.0, addressing issues related to uncertainty and performance in user schemas. These improvements include the ability to add resolvers to explicitly defined fields using extensions like @link and @dateformat, and the introduction of new inference modes such as strict inference and no inference, which allow for more controlled schema behavior and improved performance. The deprecated feature noDefaultResolvers will be supported until version 3, after which new defaults will apply, requiring users to migrate their code to the updated schema customization practices to remain compatible with future versions. These updates aim to provide clarity and flexibility, encouraging feedback from users to refine the schema customization API further.