Flash technology used in SSDs has a limited lifetime in terms of writes per location. Although SSDs have the intrinsic feature of wear leveling to attempt to spread out those writes across all locations in the device, eventually one or more locations will wear out and no longer accept data.

As there is no easy way to determine how many write cycles have occurred in an SSD prior to purchase, there is always a risk of getting a device that starts failing the day after one installs it.

The T7 series gets very hot under sustained writes, hot enough to be uncomfortable to hold, and as you've found, sometimes hot enough to shut itself down. I have also seen that problem with intermittent writes if the drive is buried under papers, so I make sure that it is on the desk with available airflow near it.

If I'm going to be doing a bulk write to fill up one of my non-Shield T7s, I literally place a metal bowl with ice directly on top of it for the duration of the transfer. But I've found that extreme step is only necessary when I'm writing continuously. YMMV.