The word so many are using to describe Matrix Resurrections is "meta" and they seem to be using it to describe their view of some social commentary in the film regarding pop culture and the legacy of the original trilogy. While that may be true to a certain extent, it is more a detail rather than the point.
In this film, as in the original Matrix, the mirror is the portal between the real world and the simulated world of the matrix. It is so because this represents the point of convergence between the outside world and the world inside ourselves; two components that constantly inform each other in our human struggle to develop identity and our own sense of self. This central theme in the Matrix films is at the heart of Resurrections; the self or identity has been manipulated to such an extent that even when one "knows" the "truth", the truth can be a weapon to enslave us. One's identity can be turned against them. Suffice it to say, maintaining one's control over self (and sanity as it were) they must constantly fight to maintain control, even as hard-fought axioms turn against us and forge the battles we'll fight on down the road.
For all of this, though, Resurrections makes a point to say that some things about our characters are ingrained rather than subject to the process of identity formation; they are hard coded, transcendental. This is why Neo finds himself back in the Matrix and once again fighting for his love, Trinity. It is why Neo is running the modal, it is why the analyst is able to exploit Neo, and it is why the war will never cease.