The Matrix Resurrections saw many of the original characters return, but Neo's trusted prophetess, the Oracle, was nowhere to be seen. The Oracle, played by Gloria Foster in The Matrix and The Matrix Reloaded and then by Mary Alice in The Matrix Revolutions, is a sapient program designed to keep the Matrix operating smoothly. The Oracle exists alongside and in opposition to the Architect, another program tasked with creating an environment for the human mind to occupy itself while machines harvest power from their bodies.
When the Architect first designed the Matrix, he found it impossible to keep the minds contained and engaged with the perfect utopian world he had created. He decided to then create a place with negative consequences and a logical system, but this too failed. It wasn't until the Architect designed a Matrix where choice played a prominent role and there was an element of hope and unpredictability in the form of the Oracle that it started to function as intended.
After the events of the Matrix trilogy, the Oracle and the Architect are on shaky terms, but a truce has been enacted, so what happens to the Oracle after The Matrix Revolutions? The primary antagonist of The Matrix Resurrections is the Analyst, who was designed to better understand the anomaly in the Matrix that manifested as the One. The Analyst appears to have taken over the role of both the Architect and the Oracle in the latest version of the Matrix. Where the Architect was concerned only with "fussy facts and equations," the Analyst is interested in human feelings and emotions and how he can use these tools to manipulate them and harvest more energy.
Why There Wasn't A New Oracle In The Matrix Resurrections
The Oracle was tasked with understanding and serving human psychology to stabilize the Matrix. This purpose and skillset evolved into an ability to predict with near-perfect accuracy the actions of humans and the resulting outcomes. The Oracle became a highly respected figure among the human resistance as she gave them direction and insight into the manifestation of the One in each iteration of the Matrix. With the Analyst's rise to power, he instituted a purge that wiped many programs from the Matrix, including the Oracle and likely the Architect as well. The Analyst saw fit to rid the system of anything that was not efficient and easy to control and manipulate from his position of power.
In the new version of the Matrix, there were very few programs that remain from the last instance; characters like Neo and Trinity are humans who were placed into the Matrix, and Morpheus, who passed away after The Matrix Revolutions, is present in a new body only because Bugs was able to create a version of him from a program Neo created. The Analyst strips the Matrix of rogue programs or potential threats that do not improve the human's output. The Oracle does not reappear in The Matrix Resurrections for the same reason as Sati's parents: because they were gone without a digital trace to create a Matrix that could more easily be controlled.