API call issue error

I am making an API call and i get the following error. The url looks fine, but i get this Error.

{
“statusCode”: 400,
“body”: {
“status”: “INVALID_DATA”,
“message”: “Issue with data for endpoint investment: [ { “key”: “User_unique_id”, “constraint_type”: “text contains”, “value”: \u001657342845533x594451766323330800” }] cannot be parsed as a JSON"
}
}