In the strictest sense of the word they _are_, but they lose a significant portion of their rights as citizens, even after serving their mandated sentence and "paying their debt to society" or whatever. I would actually argue that ex-cons aren't citizens in the practical sense specifically because they lose out on a bunch of rights they could freely exercise before their conviction.
And before we get into a debate about whether ex-cons "deserve" rights, their sentence is supposed to be them paying their debt to society. Why shouldn't their rights be restored after that?
That's a different argument though. Punished or not, they are still citizens - so clearly whether you can or cannot vote doesn't change your citizenship.
> Real is probably the wrong term here, but certainly a citizen without the full suite of rights granted to you.
I acknowledged the thing you are objecting to before you started objecting. If you want to bikeshed a loosely used term after it's been acknowledged as being the incorrect term - have fun.