Is my SSD failing?

I have a Mac Mini 2018 with a 2T SSD.

I've started to notice a few files getting corrupted, and an I/O error being reported when I try to access them.

I've run Disk Utility, and nothing bad shows up either running in recovery or normal mode.

The worry I have is that the SSD is degrading, but I'm not sure how to confirm my suspicion.

How do I tell if my SSD is dying? Or is there some other cause?

Disk drives (both HDD and SSD) keep counters relating to their activity. These go by the collective name SMART (Self-Monitoring, Analysis and Reporting Technology). macOS does not, by default, expose any of these counters.

The GUI based app for showing these is DriveDX which has a free trial period. The installation is a little unusual as it involves the installation of a kernel extension that reads the SMART data. As well as presenting drive information it includes guidance as to what the counters mean and which are important for drive lifespan and errors.

If you are comfortable using Terminal, you can install smartmontools which uses the same kernel extension as DriveDX and reports the same information but not to so pretty and without any interpretation. The install is easiest using Homebrew. If you are not familiar with Homebrew, use DriveDX.

Warning: The key weakness with reading SMART counters on macOS is that it depends on a kernel extension which is some years old and has no developer support. This is most of an issue with recent versions of macOS (particularly Big Sur). BinaryFruit (the makers of DriveDX) have packaged it (with signatures, etc.) so that it installs with as little fuss as possible, but they do not seem to be doing anything for long term support except for keeping their help pages current.

Edit: That may be somewhat unfair on BinaryFruit as I see they have released a version of the kernel extension for Apple Silicon Macs.

From the comments you have given here work the I/O errors, you’re looking at a disk or controller or cabling failure. In this case it is almost certainly a disk failure in progress.

You want to stop using the computer immediately and ensure that you have backups of everything. Then replace the disk and restore from backups.

In this case, do not rely on SMART status at all. This status can say that the disk is perfectly fine when it is definitely not, and you could risk further data loss this way.