From looking at numbers from the macOS SSD thrashing issue, we know lifetime usage as reported by SMART is not a strict function of terabytes written (at least on those SSDs). This makes sense, because small writes have a much higher endurance cost than large writes on SSDs. SSD lifetime isn't based on total bytes written, it's based on total blocks erased in the underlying Flash, and blocks are much larger than sectors so small writes necessarily cause write amplification to some extent (depending on the wear leveling).

If manufacturers are guaranteeing a certain number of TBW on SSDs but can't actually sustain that at pathological write sizes, they need to start qualifying those guarantees with e.g. an average write size statistic. Then they can claim Chia breaks that assumption and reject warranty claims in those cases.

This isn't unique to Chia. For example, a database workload will cause higher stress per byte written on an SSD than a raw video recording workload.

It's also possible they're talking about time-based warranties with daily usage numbers. Many SSDs will be "guaranteed for 5 years" at some DWPD (drive writes per day). In that case they're probably just saying Chia plotting greatly exceeds the DWPD stat and thus your number of years warranty no longer applies. That ignores the above problem and is just about how the drive endurance is specified.

(Also, just to clarify: apparently SSDs are used in Chia as a staging ground to build data to put on HDDs, which is then read only; I don't think there is any endurance cost to disks for actually "farming" Chia, only for "plotting" the contents of those disks initially; I think Chia is silly but just want to get the tech right)