Copy to Books sharing is missing for PDF files

When I open a PDF file on my iPad then I can select the option “open In Books” in the Share section. The PDF does open in Books but when I go back to the Library view, the PDF disappears.

most likely because the PDF file was not copied to Books but only opened for reading.

Despite other “Copy to...” share actions there is no Copy to Books action.

I have noticed this issue since iPadOS 13.