Open an existing Affinity Publisher document and save it under a new name. Make content changes and save. Export the updated document as a PDF. Put the PDF online and open it with Chrome. Chrome shows the PDF title as the ORIGINAL Affinity Publisher document name.
This became an embarrassment when I uploaded a PDF exported from Publisher promoting a high school art exhibit. Opening the PDF in Chrome showed a title of "wonderfulwovens," the name of the original Publisher file from 2018. (The name of the current Publisher document is simply "flyers.afpub," and it was exported to PDF as "flyers.pdf.")
The PDF export should title the PDF the same as the export filename by default, and, ideally, have the option to specify a title.
I was able to edit the PDF title in a text editor. This should not be necessary.