Cyrillic glyph issue in Firefox

Hi!

I encountered a strange issue with a Cyrillic glyph ("з"). I use the Google Font "Roboto", also because I checked that it would feature that glyph.

Now on my Wordpress page in Safari, that display works perfectly. But in Firefox, Roboto does not feature the one glyph (the rest of the text is displayed perfectly in Roboto).

Would anyone know a way how to make the glyph be displayed correctly even in all browsers?

All best,

Stefan