bug (MWE)

\documentclass{article}
\usepackage{lipsum, blkarray}

\begin{document}
\pagenumbering{arabic}
\lipsum[1-10]

a

a

a

\begin{blockarray}{@{}l}
\begin{block}{@{}l\Right{\}}{hello}}
a\\
a\\
a\\ \end{block}
\end{blockarray}

\end{document}