Lowercase "a" is different between normal font and italic

[cbraga9]

The italic variant of the letter "a" is different to the normal variant.

[kenmcd]

That is by design, so I do not think that is going to change.
But you do have a couple options.
You can apply stylistic set 01 (ss01) to Regular to get the same single-storey a.

Or you can apply stylistic set 01 (ss01) to Italic to get a different a.

Or you can do both.
As you can see ss01 also affects other characters such as the l and t.
So you may want to apply it to just the a if desired.

[juandelperal]

Hi there. Yes, that's how the design is indeed.
We are closing this issue, thanks

[cssobral2013]

@cbraga9 - As a sidenote, if you want multiplexed posture in Montserrat, please see my fork of Montserrat: https://github.com/cssobral2013/argentum-sans
Please note, however, that it has a thicker Regular weight.