[Deprecation] Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user’s experience. For more help, check https://xhr.spec.whatwg.org/.
This functionality is by design.
The synchronous ajax call is by design. Adobe Engineering team plans to change this functionality in the future by loading the file via including a script tag. However, that product enhancement won't be included in AEM until a future version.