lowercase in the generated bibliography

Question

I have a problem with my bibliography, the words in uppercase appear in lowercase in the generated bibliography as shown in the following figure:

Here is my code

\documentclass{article}
\begin{filecontents*}{test.bib}
    @article{Ref1,
        title={GGA and GGA+U study},
        author={A author, B author},
        journal={Journal},
        volume={1},
        number={1},
        pages={1--131},
        year={2025},
        publisher={Pub}
    }
\end{filecontents*}
\begin{document}
\cite{Ref1}
    \bibliographystyle{unsrt}
    \bibliography{test}
\end{document}