With unicode-math loaded, \* chooses the wrong character in slot 2 instead of 0x00D7.
Reference: https://tex.stackexchange.com/q/750832/4427
\documentclass{article}
\usepackage{unicode-math}
\begin{document}
Bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla $(x+y+z)\*(x-y+z)$ bla bla bla bla bla.
\end{document}
Proposed fix:
\RenewDocumentCommand{\*}{}{%
\discretionary{\thinspace\the\textfont 2\char"D7}{}{}%
}