Unfortunately, I can’t tell you what is causing the writes.
We don’t know what SSDs you are using, but 80GB/day is nothing to most SSDs.
Even for cheaper consumer drives, this should not exceed their TBW.
You could change the system dataset and syslog location.
Do you use RAIDZ? This could be rw amplification?
Maybe your SSD failure had nothing to do with SSD wearout and this was just a coincidence.