Unfortunately, chip manufacturing isn't perfect and some of the silicon is defective. But just because it doesn't meet the standards of a particular product doesn't mean it can't be useful in less performing variants. Therefore, manufacturers generally recycle defective silicon into lower tier products. Die recycling is common practice, and it is even more so now that we are in the midst of a global semiconductor shortage. NVIDIA has previously switched GPUs to the GeForce GTX 1650 and, more recently, EVGA to the GeForce RTX 2060 KO Gaming. Now, it seems to be the turn of the GeForce RTX 3060.
The original GeForce RTX 3060 is based on the GA106 die. However, the new variant reportedly uses the GA104 die, which is the one employed on the GeForce RTX 3060 Ti, RTX 3070 and RTX 3070 Ti. The new version will probably not have a different name; hence, we'll call it GeForce RTX 3060 GA104 for simplicity. The GA106 die is 276mm² and houses 13.25 billion transistors, while the GA104 die is a substantially larger chip, reaching 392mm² with 17.4 billion transistors. Despite the swap, the GeForce RTX 3060 GA104 retains the specifications of the original and its performance should be identical to the standard GeForce RTX 3060.
The switch from the TU106 to the TU104 die in EVGA's GeForce RTX 2060 KO Gaming revealed a negligible performance difference in games. However, testing showed, and even NVIDIA itself confirmed, that the TU104 variant would provide slightly higher performance under a certain rendering workload, such as Blender. It will be interesting to see if the GeForce RTX 3060 GA104 also shows significant advantages in a certain area.