I've never read anywhere that Plato was a slave. He came from an aristocratic family and was one of the noble youths the Athenians were so concerned about the historical Socrates corrupting with his epistemic skepticism. He had family that were apart of the anti-democratic coup d'etat.
I was also unaware of Plato's possible slavery, and found this [0], but I do not have the background knowledge judge the veracity of the information:
> One source of the story of Plato being sold into slavery is Lives and Opinions of Eminent Philosophers by Diogenes Laërtius. An English translation is available online [1] on Project Perseus. You can find the full story in Book 3 that discusses the life of Plato.
These sources just highlight that he was, at best, under threat of being a slave though, not that he was actually sold and performed as a slave. He's ransomed for at the last minute by someone recognizing him at the market.
If Plato had actually been a slave, his lifelong commitment to anti-democratic political organization would've been a little different, though maybe not, considering even this experience didn't change his philosophy, to the point that's likely not worth mentioning as a significant experience, unlike Epictectus who was born into slavery.
Framing that conflict and history as about "epistemic skepticism" is modern simplification. It makes modern point and avoids any hint of actual conflicts in that city.
It completely ignores very real and deadly politics of that city prior and reasons why Socrates was hated.
Many aristocrats could be captured as war prizes, enslaved, and used to tutor the children of the winning army. They weren’t all forced to pick cotton or worked to death.
