App incremental update problem

Hi everyone, our product is developed using the UE4.27 engine and is packaged as an apk+obb file, with a total size of about 1.8GB. After releasing new versions to AppLab or any other testing channels, users have to update the entire 1.8GB each time.

However, I remember there was a period when incremental updates were possible, meaning users only needed to update the parts that had changed. But later, it became necessary to update the entire package every time.

Has anyone else encountered this problem? Thanks