This also happened many years ago with Linksys (prior to Cisco). It’s not that uncommon for manufacturers to release new revisions of hardware without necessarily making it clear to the purchaser. If their purpose is to deliver a router and they can shave a few cents off the BOM with less RAM, but it still works with their software, why would they care. And once new revisions have been released into the supply chain, it can be hard to know exactly what version you are buying.
In the Linksys case, IIRC they eventually re-released the first revision WRT54G as the WRT54GL (for Linux), so that people who wanted different firmware could get the exact hardware they wanted.
We see this all the time with SSDs, where a high-spec model is released to reviewers, then a low-spec model is mass-produced and sold under the same model number. That's fraud, isn't it? Shouldn't it be?
In my experience, TP-Link always has the hardware revision on a label on the outside of the box.
This is even a common product development strategy: ship to market asap, optimize the margins later.
I want the most important performance characteristics that would be on a good datasheet to be maintained, even if there is no datasheet.
I bought a cellphone from them many years ago and they never really supported it and I couldn't even buy a replacement battery.
Recently I bought a router with the firm intent of installing OpenWRT, but I received a newer revision that had a different CPU, less RAM, and less flash memory.
These events left a bad impression, but they do make affordable stuff with reasonable quality.