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

What does the X4 mean in an PCIe Gen X4 NVME drive? nvme 4 0 in 3 0 slot and USB ; all these standards are backward compatible A Samsung 980 PRO PCIe NVMe SSD with 1 TB of storage capacity nvme slot vs m2 and USB ; all these standards are backward compatible A Samsung 980 PRO PCIe NVMe SSD with 1 TB of storage capacity

nvme m2 slot motherboard  speeds which is not what the question meant, imo Click to Those are just NVMe to PCIe slot adaptors so technically it is