When I type the following code in a comment:

$$\require{AMScd} \begin{CD}\Gamma(X,\mathcal O_X) @>>> \mathcal O_{X,x}\\ @AAA @AAA \\ \Gamma(Y,\mathcal O_Y) @>>> \mathcal O_{Y,f(x)} \end{CD}$$

to generate: $$\require{AMScd} \begin{CD}\Gamma(X,\mathcal O_X) @>>> \mathcal O_{X,x}\\ @AAA @AAA \\ \Gamma(Y,\mathcal O_Y) @>>> \mathcal O_{Y,f(x)} \end{CD}$$

I end up with a warning box stating: Only one additional @user can be notified; the post owner will always be notified. It seems that it confuses between @>>> in the text mode and @>>> in the math mode.

This really should be fixed.