Binary array present in response is being converted to string in react

Hi I am using axios to make backend api calls. My response object which is generated using Java has following structure

 {
      workbook: [] //array of binary data of excel file generated using apache poi
      userId:<userId>
      
   }

When I receive the response given by axios , ‘workbook’ property which is supposed to be byte array is coming as string. I am not sure if axios is converting the byte array to string. Can someone tell me What is the correct way of dealing with byte data in axios