Not making a good backup has been a problem since we have started using the personal computer. A second issue is testing the backup to see if it’s really working. People always seem surprised when it happens to them.
I guess the root cause is swapping to the SSD. When a computer is stuffed with a video rendering job for hours it runs short of ram and starts to swap out to SSD. All SSD is write limited and basically wears out. You hit the limit on the SSD “drive”.
It took you 5 months to hit the SSD lifetime limit. What makes you think it won’t happen again ? I hope for your sake the warranty is still in effect next time. Personally I think it’s a hardware design issue and Apple should upgrade the SSD when this happens. And it will happen again.