I tested this on the Google Font site and it's not working there which is how I determined that's where the problem is.
It was originally found when trying to use the tnum feature for the values of EuiProgress:
Essentially tabular numbers makes the numbers of a font behave almost like they are a monospace font so that when they are lined up in a column, they align better. Here's a screenshot of how it's supposed to behave with Inter. As I mentioned in the meeting, however, this is not currently working with the Google font. So I'll have to explore that later.

Originally posted by @cchaos in #3948 (comment)