“AMD claims that the total bandwidth of the L3 cache increases to beyond 2 TB/sec, which would technically be faster than the L1 cache on the die (but with higher latency).”
AMD glued 64 MB of SRAM on top of a Zen 3 chiplet and tripled its L3 cache. The headline gain is 15 percent in games, measured by AMD on a prototype. TSMC did the hard part. Nobody gets to buy one yet.