Some codes end up being base64, sometimes they represent special formatting before they even represent the data itself.

for example :

converting data to TLV formatting and then to base64

and when you decode it you will notice that it is not representing the correct data.

so I believe they take the data and manipulate it then convert it to Base64.

so no one can read it except their device.

the only way to read that base64 is to know how to arrange the data after converting it to hex or bytes, or the name of the algorithm they use before converting it to base64.

and also you should provide some extra information like the API, the company's website, and the things you think will provide some ideas.