I have updated the PDF but it shows the same content as in the old?

The PDF gets updated.
What happens is: if you generate multiple PDFs in a row, and open them in the same browser, your browser thinks it's the the same one and shows you the old one to save you from uploading "unnecessary data." We can not change this behaviour, it's built-in.
If this happens you can easily overcome it by open a browser window in "incognito mode" / "Private mode" and enter the address of the pdf there, then it will not have saved data and you will see new version.

You can also clear your cache, this will remove the saved version in the browsers memory

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