As the official ORD site T3 map clearly shows, the rotunda is part of T3.



You can argue all you want, but the simple fact is that according to ORD’s own website, the G gates are part of T3.

Airport signage:

Another one:

...and one more:



All other mapping sites state the same thing, the G gates are part of T3.

Here’s one of many examples;
O'Hare Gate Map - Chicago O'Hare International Airport - ORD

Another:
https://upgradedpoints.com/chicago-ohare-ord-airport

...and another: Chicago O'Hare Airport (ORD) Terminal 3 Map - Map of Terminal 3 at Chicago O'Hare airport