No, they have always been labeled as polarized plans, not extended base or anything else.
Polarized plans have been released as Early Access feature in March 2021, the earliest Dylan Johnson video on that topic was December 2020. However, that is different from the video I think you are referencing this video, though, from February 2021.
While I don’t have proof, I reckon the polarized plans had been in the works already. Our very own @mcneese.chad rolled his own polarized plans as early as 2018, so the idea definitely wasn’t new nor was it “impossible” to do polarized training with TR.