Description
As in the title. See the parts highlighted in red.

Seems like the problem is the argument is determined to be ended at the first }.
Not sure how easily fixable this is because in principle arbitrary text can appear in the second argument. But it seems to work well with \href. (I have conceal enabled which hides the \href when the cursor is away from the line.)

Steps to reproduce
Type the following in a document
%! TEX program = pdflatex
\documentclass{article}
\usepackage[colorlinks]{hyperref}
\begin{document}
\section{test section}
\label{stuff}
\hyperref[stuff]{hello $5^{23}$ world}
hello $5^2$ world
\end{document}
and observe the red characters in syntax highlighting. \lx may be needed after saving the file to load hyperref package syntax highlighting.
Expected behavior
No error happened.
Actual behavior
No response
Do you use a latexmkrc file?
Yes
VimtexInfo