I compile the following code
\documentclass{article}
\usepackage{hyperxmp}
\usepackage[pdfa]{hyperref}
\usepackage{kantlipsum}
\hypersetup{
keeppdfinfo,
pdftitle={test},
pdfauthor={sdaf},
pdfapart=1,
pdfaconformance=B,
}
\begin{document}
\kant[1]
\end{document}
and somehow I get interesting results. 
I get the backtick at the beginning of the page. I need the variables in hypersetup to get rid of the warnings. When I disable the package hyperxmp it vanishes, when I remove the option pdfa it vanishes as well.
Honestly don't know how to get rid of this backtick. Following the old question didn't help either. I've share my log temporarily
DocumentMetadataI've found only. Reviewing the document I'm not clear ifpdfmoddateand/orpdfcreationdateare supported. According to the documentation not really. But perhaps I've missed something. – LeO Jul 10 '23 at 11:54