Tipster @KOMACHI_ENSAKA claimed that internal AMD references to GCD and MCD likely refer to the "Graphics Complex Die" and "Memory Complex Die" of the purported Navi 31. These terms strongly indicate that Navi 31 (an upcoming RDNA 3 part) will likely be chiplet-based like Zen CPUs.
https://www.notebookcheck.net/AMD-s-upcoming-RDNA-3-graphics-cards-might-be-chiplet-based-like-Zen-implying-unprecedented-performance-gains.484831.0.html