Remove right bracket from footnote

Question

I inserted a footnote in a Latex template, and it suddenly shows up like this

all I did was write

...as a crossed product\footnote{...}

and I really do not know why it is showing just a right bracket there. How do I remove it?

In the .cls file that I am using, there is a section called Footnotes in which this code is included.

%-----------%
% Footnotes %
%-----------%

%% The \vfill forces footnotes to the bottom of the page,
%% which is necessary since \raggedbottom is in effect.
%% 30mm is the width of the line.
\renewcommand\footnoterule{%
  \kern-3\p@ \vfill
  \hrule width 30mm
  \kern2.6\p@}

\newcommand\xxfntext{%
  \long\def\@makefnmark{\mbox{\textsuperscript{\normalfont\@thefnmark)}}}
  \long\def\@makefntext##1{%
    \parindent\XxIndent
    \makebox[1.2em][l]{\@makefnmark}##1}
}

\xxfntext

Answer 1

The line \long\def\@makefnmark{\mbox{\textsuperscript{\normalfont\@thefnmark)}}} from the .cls class that you use contains a ) which is responsible for your undesired output. Since you prefer not to change the command definition in the .cls class itself, campa's suggestion may be the best alternative: redefining the command in your own document and omit the offending ):

\makeatletter
\renewcommand\xxfntext{%
  \long\def\@makefnmark{\mbox{\textsuperscript{\normalfont\@thefnmark}}}
  \long\def\@makefntext##1{%
    \parindent\XxIndent
    \makebox[1.2em][l]{\@makefnmark}##1}
}
\makeatother