I bought the new Samsung 980 Pro 1TB (PCIe 4.0) and put in the Lenovo Yoga Slim 7 (PCIe 3.0), I saw only ~10% decrease in raw performance : r/AMDLaptops
Samsung 980 Pro review | TechRadar
Samsung 980 Pro PCIe 3.0 NVMe 1TB Internal SSD | Nebraska Furniture Mart
Samsung 980 PRO PCIe 4.0 NVMe M.2 Internal V-NAND Solid State Drive with Heatsink 1TB | GameStop
Samsung 980 PRO SSD | Spec & Feature | Samsung Semiconductor Global