nvme drive disappears after about an hour of uptime

[dsimic]

I meant to answer this before, and had forgotten. Mine is the second revision, I believe, whichever was the first replacement for the original which needed an adjustment to fit (i.e. mine worked out of the box).

Meh, now I cannot recall whether the preproduction revision or the first "official" revision of the NVMe adapter had to be modified to fit the PineBook Pro case.

Nice finds! I took a glance at the documentation. What is it that makes you say they shouldn't be lifetime counts? I see nothing claiming for or against, but I do see: "A value of 0h, indicates that this transition has never occurred or this field is not implemented." Particularly, "never occurred" as opposed to something like "has not occurred since uptime" would infer that it's more likely a lifetime count (I'm just basing this on the wording; I'm mostly unfamiliar with this technology).

Those shouldn't be lifetime counts based on this discussion, although the NVMe specification has no mention of the lack of persistence.  That may also be a highly drive-specific violation of the NVMe specification.  Could you, please, try powering your PineBook Pro off and back on, to check if those values will reset to zero?

It's also unclear what exactly those thermal thresholds are. I'm not seeing anything in my smart report to indicate what temperatures, so while PS 2 is the only power state available to it currently, I'm guessing it's possible the threshold is such that it's running the function which adjusts those values without actually switching power states.

Interestingly, pages 221-222 of the NVMe specification state that those two thermal throttling thresholds (temp1 and temp2) may be configurable, of course within the respective drive-provided temperature ranges.  The effects of reaching those thresholds, however configured, may be transitions to lower power states, or some other form of vendor-specific controller throttling, as stated on page 322 of the NVMe specification.