The proposal is to introduce the ability to register and unregister glTF extensions during export (e.g., KHR_texture_transform).
Currently, the default serializer impliments several extensions, but developers might need the flexibility to override this behavior or add support for custom extensions during the export process.
The glTF loader already provides similar functionality, as detailed here: Babylon.js Documentation - glTF Extensions. It would be ideal to implement comparable functionality for exporting.
GLTFExporter is protected, as it contains various low-level behaviors.
However, exposing GLTFExporter.RegisterExtension and GLTFExporter.UnregisterExtension would be a simple and effective solution to achieve this goal.