Arrow Label Size Issue in Tikz-CD

I am using the mathtools package in combination with the tikz-cd package to decorate an arrow label with an overbracket. However, using the \overbracket within the arrow labeling messes up the automatic vertical-height adjustment of tikz-cd.

The above comes from the following minimal working example:

\documentclass{standalone}\usepackage{tikz-cd,mathtools}\newcommand{\CompB}[1]{\overbracket[.5pt][1pt]{#1}}\begin{document}\begin{tikzcd}\CompB{M} \ar[rr,"{\CompB{f}}" near start]\ar[rr,"\overbracket{f}"]\ar[rr,"f" near end] && N\\& M \ar[ul,"b"]\ar[ur,swap,"f"] &\end{tikzcd}\end{document}

In included two labels for the upper arrow to highlight the problem (and to test whether the problem is my slight redefinition of the overbracket). I was not able to get something helpful out of the tikz-cd documentation, but I might have overlooked something.

How can I readjust the height of \overbracket{f} in the tikz-cd arrow label correctly? And why is this happening?

Thanks in advance!