I have an SK Hynix M.2 NVMe 1TB that starts out writing like it is advertised. Then shortly after beginning of benchmark the write rate drops like it hit a wall from 3.2 GB/s to 1.2 GB/s. I don't have enough knowledge of nvme drives to know if this is to be expected or if it is something I can change via settings. It just doesn't look right.
benchmark screenshot
benchmark screenshot