为什么副标题为 Ck，算法的行号不断覆盖？

Question

\documentclass[dvipsnames,svgnames]{beamer}
\usepackage{algpseudocode}
\usepackage{eulervm}
\usepackage[most]{tcolorbox}

\setbeamercovered{transparent=40}

\usefonttheme[onlymath]{serif}
\usefonttheme{professionalfonts}

\newcommand\myRed[1]{%
  \makebox[0pt][l]{\hspace*{-\algorithmicindent}\textcolor{red}{#1}}}

\tcbset{
common/.style={
  arc=0pt,
  outer arc=0pt,
  boxsep=0pt,
  left=1pt,
  right=1pt,
  top=1pt,
  bottom=1pt
  },
blue/.style={
  common,
  colback=LightBlue!90,
  colframe=LightBlue!90,
  highlight math style={colback=LightBlue!50,colframe=Navy,boxsep=0pt}
  },
green/.style={
  common,
  colback=Green!50,
  colframe=Green!50,
  highlight math style={colback=Green!50,colframe=Green}
  }
}

\begin{document}

\begin{frame}<1>
\begin{algorithmic}[1]
\uncover<2>{\If{$quality\ge 9$}}
\uncover<2>{\State $a\gets perfect$}
\uncover<2>{\ElsIf{$quality\ge 7$}}
\uncover<2>{\State $a\gets good$}
\ElsIf{\tcbhighmath{k\ge 5}}{\State  $a\gets medium$ \myRed{$c_k$}}
\ElsIf{$quality\ge 3$}{\State\myRed{$c_k$} \tcbhighmath{$a\gets bad$} }
\Else
\State $a\gets unusable$
\EndIf
\end{algorithmic}

\end{frame}

\end{document}