Is Nibbana a different reality, or just a different state of mind?

Is Nibbana some sort of transcendent reality to which an Arahant gains access, or just a mind liberated from the taints? Or both? Or neither?

I find sutta passages like this rather ambiguous:

"There is, bhikkhus, a not-born, a not-brought-to-being, a not-made, a not-conditioned. If, bhikkhus, there were no not-born, not-brought-to-being, not-made, not-conditioned, no escape would be discerned from what is born, brought-to-being, made, conditioned. But since there is a not-born, a not-brought-to-being, a not-made, a not-conditioned, therefore an escape is discerned from what is born, brought-to-being, made, conditioned."
https://www.accesstoinsight.org/tipitaka/kn/ud/ud.8.03.irel.html

What do you think?