markboth inside tikz node text not working

If markboth is used inside a tikz node text, this markboth does nothing.

• Output of pdflatex, xelatex, and lualatex are the same.
• Does this work as expect?
• I noticed that an inside-group markboth, like {markboth{lefthead}{righthead}}, still works. Then what does tikz do that “blocks” markboth?

documentclass{book}
usepackage{tikz}

begin{document}
tikznode[red] {markboth{tikz left}{tikz right}};
contents newpage contents
end{document}

---

Where does this question raise from:

• The standard document class uses something like chapter*{...martboth{...}{...}} inside tableofcontents to generate the title of toc and change the marker.
• In some fancy section heading styles, the argument of chapter[*]{arg} is passed to a tikz drawing.
• So with these section styles, tableofcontents fails to change marker.

I know how to make a workaround, but I am curious about how and why it fails.