YouTube has restored some channels focused on nootropics, the broad category of supplements that supposedly improve cognition, after they were wrongly deleted for violating the site’s community guidelines.

“With the massive volume of videos on our site, sometimes we make the wrong call,” YouTube told Motherboard in a statement. “When it's brought to our attention that a video or channel has been removed mistakenly, we act quickly to reinstate it. We give uploaders the ability to appeal these decisions and we will re-review the videos.”

“It behooves us to use our enhanced brains to figure out what is going on and how to stop it.”

At least five channels were deleted in less than a week, prompting an outcry from the affected YouTubers and fears that the site was about to be purged of "smart drug" content. YouTube has ramped up moderation over the past six months in response to a wave of bad press that highlighted the prevalence of violent, offensive videos and conspiracy theories on the site. In March, the company started banning videos made to sell guns or demonstrate how to make guns or gun accessories.

“It looks like YouTube is aggressively going after fellow neuronauts and taking down their nootropic channels. I find this rather alarming because it may be a harbinger of things to come,” one user posted on the r/nootropics subreddit. “It behooves us to use our enhanced brains to figure out what is going on and how to stop it.”

Three of the deleted channels have been restored, including Nootropedia, EpicBeasts, and Steve Cronin’s eponymous channel. The ones that remain deleted at the time of publication are Ryan Michael Ballow’s Cortex Labs Nootropics, which had more than 7,000 subscribers, and Jonathan Roseland’s channel Limitless Mindset, which had more than 13,000 subscribers.

YouTube’s messaging to creators who violate the rules also tends to be vague, leaving questions about which parts of a video violated which aspects of its community guidelines. Nootropics YouTubers who were penalized weren’t sure if they’d violated a provision against “harmful or dangerous content” or if they’d been flagged for spamming because they promoted products. This lack of transparency lends itself to conspiracy thinking: Ballow said he believed YouTube was engaged in censorship on behalf of the pharmaceutical industry, while Roseland called it a symptom of YouTube’s “intellectual authoritarianism.” Roseland has moved his content to DTube, an alternative video site with lax moderation that is supported by peer-to-peer payments instead of advertising.

“Sounds like a couple of reviewers made mistakes.”

When Steve Cronin first got a strike against one of his videos—a review of a product he had bought at Whole Foods—he had to guess at what YouTube was penalizing him for. He set 101 videos to private in order to ward off more action. Instead, he got another two strikes, which prompted him to delete 263 videos. Then, his account was deleted anyway.

“Their community guidelines are vague, probably so they can be enforced broadly,” he told Motherboard in an email.

He appealed his channel deletion, but it was denied. YouTube told him that it had “carefully reviewed your account appeal” and his account was “terminated due to repeated or severe violations of our Community Guidelines on Spam.”

However, the termination was reversed just a few hours later—possibly due to the intervention of a member of YouTube’s Contributors and Trusted Flaggers programs, two volunteer moderation programs administered by YouTube.

The member, who spoke to Motherboard through the Twitter account @Contributors_YT, said Ryan Michael Ballow’s account was rightly deleted for spam, but that Cronin’s was an error.

“Steve's, from the sounds of it, was a mistake; with the title containing ‘smart drug,’ a reviewer probably thought it was about drugs and struck it,” they wrote. “Sounds like a couple of reviewers made mistakes.”

Members of the Contributors and Trusted Flaggers programs do not have the ability to reinstate channels, but “We do get some inside contacts that we can push reviews to if we feel the channel did not violate any rules,” they said. When asked if that’s how Cronin’s deletion got reversed, they said, “Yes. My appeal for him got the channel reinstated.”

Cronin’s 22,000 subscribers are back—but since he deleted his videos himself, they’re still gone.