How to write a blob string as a PDF and save it in Python?

I want to save a string from a blob I received through a Javascript injection/API POST through Selenium execute_script() in Python on a homepage to receive a PDF, as the actual PDF on my computer.

Together with the POST (includes charset=UTF-8) and some other things I did this in the execute_script():

 const data = await downloadResponse.blob()
        const reader = new FileReader()
        reader.readAsBinaryString(data)
        const str = await new Promise((resolve) => {reader.onload = () => {resolve(reader.result)}})
        return str

and saved the result in “test”.
test then looks something like the very long string (I shortened it, it is a whole PDF file as a string after all if I understand correctly) at the end of this description.
How would I go about saving that as an actual PDF now?

I did try

config = pdfkit.configuration(wkhtmltopdf=r"C:Program Fileswkhtmltopdfbinwkhtmltopdf.exe")
pdfkit.from_string(test,'test.pdf', configuration=config)

and

with open('test.pdf', 'wb') as output_file:
    writer = PdfWriter()
    stream = io.BytesIO()
    stream.write(pdfkit.from_string(test, False, configuration=config))
    writer.add_page(PdfReader(stream).pages[0])
    writer.write(output_file)

to no avail. They both save a file called test.pdf but it is not actually a readable PDF. Its just a bunch of text starting like the long raw string.
I have the idea that I need to format or cut the string before passing it through those functions, but I have no idea how.

‘%PDF-1.4n%ª«¬xadn1 0 objn<<n/Creator (Apache FOP Version 2.7)n/Producer (Apache FOP Version 2.7)n/CreationDate (D:20230802212617+02’00’)n>>nendobjn2 0 objn<<n /N 3n /Length 3 0 Rn /Filter /FlateDecoden>>nstreamnxx9cíx99gPTYx16x80ï{x9dx13rÝMx93¡ÉI¢x84x06$ç$9x8ant7x99x16x9ax0c*x8ax0cx8eÀx08″”Ix11Dx14pÀÑ!È(*¢x18x10x05x05TÔidx10PÆÁQDEeiü1»5?¶¶jkÿlx9fx1fï}uî©wÎ}u«ÞWõx00x90!&°

[…]

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[…]
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