On February 9, 1998, Star Trek Deep Space 9 broadcast one of the most important episodes in the entire history of the franchise.
And what it said about society back in 1953 was just as relevant as for 1998. And perhaps even more important for 2021.
Others have written more eloquently about the plot line, the characterizations, the background, the actors (Avery Brooks directed himself, and his performance should have earned him an Emmy). So I’ll just link to:
Avery Brook’s “proudest moments” interview
DS9 Season 6 Extras – the actors speak (Armin Shimerman calls it “perfect science fiction”)
Star Trek Official Website: Remembering “Far Beyond the Stars”