Nice digging, that lines up perfectly with the observed behavior! I'll have to poke around and see if anything indicates that's the operational mode to be sure.

The failure mode was that one day I just noticed it was copying sequential data from another drive slower than it normally did. Don't recall it ever having been touched after install (it is the heatsinkless variant of the T705 4TB mounted on the motherboard m.2 hearsink for that slot). Temps always reported quite reasonable, even when under stress bench load (which was rare, the drive was just a secondary drive for loading games). Since then it's been popped between about 10 boards in confusion though haha. No cat yet!