Can unicode characters which are not part of font family be rendered from fallback font family set?

I'm using font family Monserrat to render Unicode subscript characters. These are computed values from Chrome Dev tools inspector:

Body of this element is

CH₂O₂ - example 2

and result looks like this:

Subscript characters are looking different then 2 in the end of this example.

Is there a possibility that subscript characters were taken from some other fallback font? And if YES, how to check which font family was applied to them?