How to correctly encode a string for unzipping with zlib in Python

I am writing a Python function that receives a string and decompresses the string using zlib.

I am trying to translate from the following Go code to Python, that I know works (please excuse the one letter variable names, this code was written by someone else):

var b bytes.Buffer
r := bytes.NewReader(s) // s is a []byte
z, err := zlib.NewReader(r)
if err != nil {
    // Error handling
}
_, err = io.Copy(&b, z)
if err != nil {
    // Error handling
}
err = z.Close()
if err != nil {
    // Error handling
}

The data is always received in Python as a string type rather than a bytes or byte array type - this is outside my control. (For more context, see below.)

How can I properly encode or convert the string to a bytes object that will be accepted by zlib.decompress?

Do I need to set the wbits parameter to something in particular?

Here is what I tried so far:

uncompressed = zlib.decompress(s.encode())

I am getting this error:

zlib.error: Error -3 while decompressing data: incorrect header check

I also tried

uncompressed = zlib.decompress(bytearray(s, 'utf-8'))

and

uncompressed = zlib.decompress(bytes(s, 'utf-8'))

but both failed with the same error.

Additional context

For those who are interested, here is some further context.

The system I am working on serializes a Go struct and sends the data as a raw array of bytes over the network. To save bandwidth, a portion of the data is compressed before serializing to bytes.

The reason the Go code always gets the data as a []byte is because it can unmarshal the JSON raw bytes with json.Unmarshal, like this:

env := RedactedStructName{}
err := json.Unmarshal(buf, &env) // buf is a []byte

I did not include this code above because I wanted to keep my question as simple as possible. In Python, the RedactedStructName struct does not exist.

On the other end, the Python program that I am working on needs to deserialize the data and decompress the compressed data so that it can work on it.

The data, when passed through json.loads, produces a Python dictionary. The compressed payload is a value in the dictionary. I don't know why, but json.loads always causes the compressed data to be a Python string rather than a Python bytes or bytearray object.