None of the other brands seen advertising on XShorts provided comments by press time.

A Meta spokesperson said in an email: “We have removed this app from Audience Network for violating our policies. We have strict policies publishers must follow to place ads into their apps.” 

Mark McEachran, a vp of product at Basis said in an email that XShorts is “a relatively new app…whose inventory is available on many SSPs.”

He noted that although the user-generated content on the platform includes adult content, XShorts went undetected because it was not flagged as an adult content platform.

“We have now blocked its inventory from our system,” McEachran said, “and have reported it to Google for violating its developer policy.”

He added that “the vast majority of inventory bought through Basis is brand safe and we have a strong track record of working only with suppliers that provide appropriate inventory for our clients.”

InMobi shared McEachran’s concern about the app’s ‘Teen’ categorization in the Google Play store. A spokesperson for for the adtech company said the company uses “publicly available indicators—including App Store and Google Play classifications—to assess the nature of an app’s content for the pre-approval stage.” They added that inMobi has “flagged this and marked all content from XShorts as mature.”

A Moloco spokesperson pointed to its brand safety policy and said the company “cannot comment on this specific incident.” 

Both Epsilon and AppLovin declined to comment. Other ad servers seen transacting on XShorts, including Amazon and inMobi did not respond by press time.

For advertisers, getting brand safety right can be extremely complicated.

“This whole ecosystem is sort of like the subprime mortgage thing, where there’s really bad inventory repackaged with high quality inventory, and they say, ‘It’s good inventory!’” the source said.

It can also be difficult to monitor where ads run as emerging platforms and sites gain popularity.

“There are so many things to keep on top of as new properties arise, as with XShorts,” said Neal Thurman, cofounder of the Brand Safety Institute and the director of the industry group the Coalition for Better Ads. He noted that because there are so many social media and ad platforms, marketers and agencies have to manage many settings to make sure campaigns only run in brand-safe environments.

ADWEEK was unable to determine whether the advertisers on XShorts use third-party brand safety tools like those provided by DoubleVerify and Integral Ad Science for pre- or post-bid filtration.