Math mode in markdown is no longer rendered as LaTeX

Summary

The markdown guide for gitlab specifies a math mode that uses KaTeX to render math expressions using LaTex. This used to work until recently but seems to be broken on the current release.

Steps to reproduce

The example markdown content:

This math is inline $`a^2+b^2=c^2`$.

This is on a separate line
```math
a^2+b^2=c^2
```

is now only rendered as code but not using KaTex (see the rendered markdown of https://docs.gitlab.com/ee/user/markdown.html#math)

Example Project

https://gitlab.com/_fgrosse/markdown-math-bug/blob/master/README.md

What is the current bug behavior?

Markdown is not rendered using KaTeX.

What is the expected correct behavior?

Math mode in markdown should be rendered using KaTeX as advertized in the documentation.