Another clue that the ssd is near its end of life is its very high Average Block Erase Count (one of the SMART attributes). On my Crucial MX500 ssd, each increase of 15 results in a 1% decrease of Remaining Life.
I reduced the frequent writing of temporary files to ssd by moving them to a hard disk. In some cases, the corresponding app is hard-coded to expect its files to be located on the system drive (the C: ssd in my Windows system) but setting up symlinks solved that problem. An example is the CyberPower UPS software, which frequently writes UPS status to a folder on C: and needed a symlink. I'm not a user of FreeNAS but googling tells me it supports symlinks too.