The phrase “AI” started out meaning a computer that was actually sentient
When did anybody use it that way?
It's literally impossible to determine for a fact that something or somebody (outside of oneself) is sentient, and our best guess for something being sentient has a requirement for having a nervous system, which artificial computers at least usually do not have, and I'm pretty sure that it did not start getting used in the context of artificial biological computers in mind.
I don't think anybody ever used the word 'AI' that way.
Pretty sure that 'AI' was never an actual term. Just a way to refer to sufficiently capable computers (with standards depending heavily on context, but I'm pretty sure usually including the ability to learn in some way).