The manufacturer is likely clearing room for the eventual ThinkBook 15 G3 model with AMD Ryzen 5000U series options later this year. If you want a prosumer laptop for a budget price, then this deal will check a lot of boxes.
https://www.notebookcheck.net/Lenovo-clearing-stock-on-AMD-ThinkBook-15-G2-for-only-654-USD-with-1080p-IPS-display-Ryzen-7-4700U-16-GB-RAM-and-512-GB-PCIe-SSD.545168.0.html