Well, I received a keychron keyboard a few days ago. I ordered a used K1 v5 (Keychron does small, infrequent production runs so it was out of stock everywhere). After some examination, I've received a v4. It's the previous gen mechanical switch instead of the current optical switch. Someone apparently peeled off the sticker with the model and serial number and one key stabilizer is broken from wear, which strongly implies someone bought a v5 and returned a v4 they already owned. Apparently this is a common scam on Amazon now
This is a tangent, but I just looked at Keychron's website, and I don't know how someone is supposed to choose from all the models and options. And there seems not to be a "comparison" page on their site.