Edit: I just saw it's about ssds and not hdds, but while Backblaze might not have stats on those, I'm fairly sure my comment still applies. Not 100%, but I assume they account for failures due to predicable issues like write wear.
There are other comments in this thread that go into this, but your comment doesn't apply. Another poster used the light bulb analogy well to describe SSD failures.
It's very common to see SSDs that were purchased at the same time, that were likely manufactured in the same batch, fail within hours of each other. Im' pretty sure I even read this fact on Backblaze.
I mean, I can see a power issue taking out all at once. It could be that. What other way would 3 disks fail at once?
I just have scripts that write key data from "mdadm -D /dev/md$N" to logs. But then I need to remember to review the logs regularly.
Like in the joke.
Our data storage was so well designed, that when first disk died, we didn't notice. When second disk died, we also didn't notice. When third disk died, we noticed.