Transcend MTE115S NVMe M.2 SSD, Up to 3,200MB/s Read, PCIe 3.0, 250GB–2TB

Single-sided at 2.23mm and built around low power draw, which is the case for putting it in a thin laptop or a small-form-factor box where clearance beneath the M.2 heat spreader is tight.

Gen3x4, so a newer slot adds nothing — and some motherboards wire their second M.2 socket at x2, halving bandwidth again. Read the board manual before concluding the drive is at fault.