Raise by theThe code for \depthtext depth: is
\documentclass[tikz,\tikzoption{text border=1cm]depth}{standalone\def\tikz@text@depth{#1}}
and the initial value for \tikz@text@depth is empty.
Reset it locally to empty.
\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[text depth=0pt]
\node[draw=red, inner sep=0pt]sep=0pt,text {\raisebox{\depth}depth=] {$\frac{1}{2}$}};
\end{tikzpicture}
\end{document}
Raise by the \depth:
\documentclass[tikz, border=1cm]{standalone}
\begin{document}
\begin{tikzpicture}[text depth=0pt]
\node[draw=red, inner sep=0pt] {\raisebox{\depth}{$\frac{1}{2}$}};
\end{tikzpicture}
\end{document}
The code for text depth is
\tikzoption{text depth}{\def\tikz@text@depth{#1}}
and the initial value for \tikz@text@depth is empty.
Reset it locally to empty.
\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[text depth=0pt]
\node[draw=red, inner sep=0pt,text depth=] {$\frac{1}{2}$};
\end{tikzpicture}
\end{document}