My old iPhone 7, before I eventually replaced it, would sometimes just die due to this as the battery aged (I kept the slowdown setting turned off). AFAIK it is _not_ a thing in any version after the 7 (or maybe 8?); certainly my 11 had a significantly degraded battery by the end (I kept it for four years), and didn't suffer this issue.

EDIT: Actually, I think this article is a _little_ inaccurate, or at least confusing:

> thus preventing the handsets from rapidly running out of juice and powering off.

IIRC the issue was, more precisely, that the SoCs had insufficient voltage smoothing to reliably tolerate full power draw at lowered voltages, and would shut off randomly. I assume the fix was, pretty much, more capacitors.