Is it updated somehow?

[Igreh]

I wonder your autoprefixer.js file contains caniuse db inside. Is it possible to update its data?

[Nebual]

It can update itself by running $autoprefixer->update();, which simply fetches from https://raw.github.com/ai/autoprefixer-rails/master/vendor/autoprefixer.js . That repo appears to update the blob quite often.