@User the error is in how

atob

is used in the frontend. It should be changed to this:

function b64DecodeUnicode(str) {
    return decodeURIComponent(Array.prototype.map.call(atob(str), function (c) {
        return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2)
    }).join(''))
}

let tokenInfo = JSON.parse(b64DecodeUnicode(frontToken))

console.log(tokenInfo);