Wikimedia Bugzilla is closed!

Apologies if this is a duplicate, I could not find it. As of today (and possibly a few days before, though not long) it seems all math rendering is broken. For instance, have a look at:

https://en.wikipedia.org/wiki/Likelihood-ratio_test

where there is clearly correct TeX code generating an error ("Failed to parse(unknown function '\begin')"). I browsed a bit further and this and similar errors pop up on several different pages featuring equations.