Ah, so maybe that was always only an issue on Linux, it’s fine on Windows.

No it was a cross platform issue when I wrote the article. It's pretty fundamental to how most engines render text. That said, text rendering generally involves some amount of platform-specific APIs to get a "native" look and feel.

I still see it on the latest Firefox nightly on MacOS. I know Windows DirectWrite handles the issue (which is why Edge handles this issue so well), so if the that's being used more it would probably help.