Bringing up the gaffe, a Twitter user wrote: ‘In this episode, Karl speaks but you hear Lenny’s voice?

Source: https://metro.co.uk/2023/01/06/the-simpsons-writer-on-truth-behind-predicting-9-11-conspiracy-theory-18051995/

It definitely did not have the same kind of — I didn’t feel as puffed up as I usually do performing Lenny’s bits on the show, because the audience was a lot less giving.

Source: https://decider.com/2023/05/26/luke-kirby-lenny-bruce-death-marvelous-maisel-series-finale-interivew-spoilers-kitty-bruce/

The rare cancer, which affects the retina, runs in families, with Lenny’s dad Jack, 28, losing an eye to the disease.

Source: https://www.kentonline.co.uk/thanet/news/brave-one-year-old-battling-eye-cancer-for-the-second-time-298254/