Many Reddit users are boycotting the social media site X, formerly known as Twitter, after Elon Musk twice made a gesture during President Trump’s inaugural celebration that drew comparisons to the Nazi salute.

Mr. Musk, the billionaire owner of the social media platform, was speaking at a celebratory rally after Mr. Trump’s installment as the 47th president on Monday when he grunted, placed his hand over his heart and lifted his arm with the palm facing down in a hail to the audience.

Although Mr. Musk played down the criticism, speculation about the gesture’s meaning broke out online, including on Reddit, where people gather in thousands of forums known as subreddits to discuss niche interests, including hobbies, sports, celebrity gossip and geopolitics.

By Tuesday, a proposal had emerged in dozens of Reddit groups across a wide spectrum of interests: Many users wanted to place a ban on linking to X posts as a way of boycotting the platform and Mr. Musk.

A moderator of a subreddit devoted to Formula 1 racing said that it would ban content from X “for a trial period.” Links from X are now also banned in r/newjersey, the moderators of that forum said in a post that was accompanied by a photo of Mr. Musk emblazoned with a red block symbol. (Other place-centered forums had similar posts.) TwoXChromosomes, a space centered on women’s perspectives, said that a bot would automatically remove X