Owing to a mishap with the Pi 4 model B I use for testing—more on how Red Shirt Jeff ruined that board later this week—I had to go buy a new Pi 4 last week.
The local Micro Center only had the 8 GB model in stock, so I went a little over budget and bought it. When I arrived home, I checked the board, and noticed a bit of a difference on the Broadcom SoC:
Can you spot it? The model number of the BCM2711 chip on this board is 2711ZPKFSB06C0T, which is the same as the chip found on the Pi 400.
This is a newer stepping of the original Pi 4 model B chip, which has the model number 2711ZPKFSB06B0T. The difference is the third-to-last character, the C versus the B.
Apparently 8 GB models may have had that version of the chip since their introduction in 2020, if this GitHub comment by pelwell is to be believed. But according to a few others, even the 2 GB model produced in the past year have this newer C0 stepping:
I found the invoice from April 13th, so that's the earliest date we know of this new SoC in a Pi 4B for now pic.twitter.com/zLl5QfXRgm