Fix invalid body data when Content-Type is application/json

[ddbdzung]

Issue Reference : #331 , #4861 , #4857

Problem

Axios requests with Content-Type: application/json were not properly serialized, causing incorrect payloads.

Solution

• Convert request body to a JSON string using JSON.stringify().
• Ensure consistency when sending JSON data.

Impact

✅ Fixes incorrect payload formatting.
✅ Ensures API compatibility.

[CuriousCorrelation]

Hi @ddbdzung, this PR you raised is a good way to fix the serialization issue on the extension side, the current PR raised at the mono-repo around similar ser/de issue addresses several additional concerns including other interceptors and maintaining backwards compatibility. So please feel free to keep this PR open for future considerations. Thanks!