The press conference was about further study of a corridor discovered ca. 2016.

From the linked Reuters content:^1

>A hidden corridor nine metres (30 feet) long has been discovered close to the main entrance of the 4,500-year-old Great Pyramid of Giza, and this could lead to further findings, Egyptian antiquities officials said on Thursday.

According to the research article^2 published 2 Mar. 2023 in Nature Communications:

>In 2016 and 2017, the ScanPyramids team reported on several discoveries of previously unknown voids by cosmic-ray muon radiography that is a non-destructive technique ideal for the investigation of large-scale structures.

>Among these discoveries, a corridor-shaped structure has been observed behind the so-called Chevron zone on the North face, with a length of at least 5 meters.

Emphasis added.

^1 https://www.reuters.com/world/middle-east/scientists-discover-corridor-great-pyramid-giza-2023-03-02, last updated 3 Mar. 2023 7:04 AM UTC, retrieved 3 Mar. 2023 11:29 PM UTC

^2 Procureur, S., Morishima, K., Kuno, M. et al. Precise characterization of a corridor-shaped structure in Khufu’s Pyramid by observation of cosmic-ray muons. Nature Communications 14, 1144 (2023). https://doi.org/10.1038/s41467-023-36351-0

ETA: annotations.