I assume the chips in this thing are a bunch of lower-binned chips that were otherwise destined for iPhones. It's not uncommon for them to ship binned variants

I assume the chips in this thing are a bunch of lower-binned chips that were otherwise destined for iPhones. It's not uncommon for them to ship binned variants under the same name. They ship 8- and 10-core GPU variants of the base M3, and iirc the entry-level M1 MacBook Air had 7 GPU cores while the next config up had 8.