Lots of people are pressuring Substack to censor what can be written on their platform. Left-wing activists trying to get antivaxxers kicked off, right-wing activists trying to get pro-Palastine writers kicked off, prudes trying to get sex workers kicked off, etc.

Substack has thus far rejected them all, sticking to a relatively minimal policy of banning incitement to violence, sexual nudity, and doxxing and personal harassment, but allowing almost anything else. But of course Twitter also started out advertising itself as "the free speech wing of the free speech party", and that didn't stick around.

This market resolves based on whether Substack's policy changes in a way that I feel is closer to "censorship of unpopular viewpoints" than "reasonable restrictions on antisocial speech". As this is subjective, I won't bet.

(The ban on nudity already counts as censorship of unpopular viewpoints, but since it's already in place, it doesn't count for this market. Only if they add additional restrictions does this resolve YES.)

A single instance of deplatforming is enough to count, even if Substack claims it was an exception or reverses it later.