% \documentclass[a4paper]{book} % works
\documentclass[a4paper]{memoir} % the citation on page 3 points to
% page 1
\begin{filecontents}[overwrite]{\jobname-refs.bib}
@article{test,
author = "Test Testson",
title = "Test",
journal = "Some journal",
year = 2020,
}
\end{filecontents}
\begin{filecontents}[overwrite]{\jobname-a.tex}
\chapter{Test}
\cite{test}
\printbibliography[heading = subbibliography]
\end{filecontents}
\begin{filecontents}[overwrite]{\jobname-b.tex}
\chapter{Test}
\cite{test}
\printbibliography[heading = subbibliography]