Thank you for reporting a bug to Unity.
After reviewing this issue, we have determined that the observed behaviour is as designed. The Pointer_stringify() function has been deprecated and is no longer supported. For string conversion, we recommend using UTF8ToString() instead.
For more information on this change please refer to our documentation here: [Change Pointer_stringify() to UTF8ToString|https://docs.unity3d.com/Manual/web-interacting-browser-deprecated.html#pointer_stringify].
If you have any further questions, please let us know.