Here is one of the many ways to do that. (See here and in its linked posts for earlier discussions.) EDIT: In order to avoid jumps, one can add the [t] option to the frame.
\documentclass{beamer}
\usetheme{metropolis}
\setbeamertemplate{footline}{}
\makeatletter
\def\beamer@framenotesbegin{% at beginning of slide
\usebeamercolor[fg]{normal text}
\gdef\beamer@noteitems{}%
\gdef\beamer@notes{}%
}
\makeatother
\usepackage{lmodern}
\usepackage{tcolorbox}
\usepackage[USenglish]{babel}
\usepackage[latin1]{inputenc}
\usepackage{bigdelim}
\setbeamersize{text margin left=10mm,text margin right=10mm}
\setbeamerfont{frametitle}{size=\small}
\begin{document}
\maketitle
\begin{frame}[t]
\frametitle{Spectral Properties}
\resizebox{\textwidth}{!}{%
\begin{tabular}{r@{\,}|c|c|}
\cline{2-3}
& \textbf{Column 1}\footnotemark[1] & \textbf{Column 2}\footnotemark[2]\\
\cline{2-3} \cline{2-3}
\color{green}\ldelim\{{3}{*}[\color{red} Info]&
Some Text & Some Text
\only<2->{\\ \cline{2-3} &Some Text & Some Text}
\only<3->{\\ \cline{2-3} &Some Text & Some Text}
\\ \cline{2-3}
\end{tabular}
}
\end{frame}
\end{document}

Another trick is to make the offending line white.
\documentclass{beamer}
\usetheme{metropolis}
\setbeamertemplate{footline}{}
\usepackage{colortbl}
\makeatletter
\def\beamer@framenotesbegin{% at beginning of slide
\usebeamercolor[fg]{normal text}
\gdef\beamer@noteitems{}%
\gdef\beamer@notes{}%
}
\makeatother
\usepackage{lmodern}
\usepackage{tcolorbox}
\usepackage[USenglish]{babel}
\usepackage[latin1]{inputenc}
\usepackage{bigdelim}
\setbeamersize{text margin left=10mm,text margin right=10mm}
\setbeamerfont{frametitle}{size=\small}
\begin{document}
\maketitle
\begin{frame}
\frametitle{Spectral Properties}
\resizebox{\textwidth}{!}{%
\begin{tabular}{r@{\,}|c|c|}
\cline{2-3}
& \textbf{Column 1}\footnotemark[1] & \textbf{Column 2}\footnotemark[2]\\
\cline{2-3} \cline{2-3}
\color{green}\ldelim\{{3}{*}[\color{red} Info]&
Some Text & Some Text\\ \cline{2-3}
\onslide<2->{&Some Text & Some Text\\ \cline{2-3}}
\onslide<3->{&Some Text & Some Text \\ \cline{2-3}\arrayrulecolor{white}}
\end{tabular}
}
\end{frame}
\end{document}

[t]option to the frame (I do that in all my frames precisely because I like to use\pause), or just make the last, stray line white. – Mar 08 '20 at 01:37