They stopped updating it in July 2020, but this is that chart with regards to Rust vs C++ in Firefox: https://docs.google.com/spreadsheets/d/1flUGg6Ut4bjtyWdyH_9e...

It's not an animated pie chart, but you can look at the complete data here :

https://docs.google.com/spreadsheets/d/1flUGg6Ut4bjtyWdyH_9e...

Source: https://wiki.mozilla.org/Oxidation

Because this site is actually driven by github, of course the weekly raw data that drives it is in a git repository, so you can dredge that repository for the weekly changes and build your own charts.

But in essence things have not changed dramatically in some months, so far as I know there are no current Firefox pushes to land big pieces of new Rust, or to Oxidise large pieces of Firefox.