Is it okay to put Gen 3 SSD in my motherboards Gen 4 pcie slots?

In this video, I tested the PCIe gen 3 slots to see if there is any performance difference when

One lane of PCIe = 16Gbs , and as NVMe requires 4 lanes, with the new PCIe technology being released, with the the new

nvme slot vs m2 Im looking to upgrade my rig, but still want to use this SSD If I was to get an x570 board that has PCIe , will this nvme drive still work

nvme m2 slot So, the PCIe or third-generation card will function when installed in a PCIe or second-generation slot as the PCIe standard is such that it is both