While Jitsi is open-source, most people use the platform they provide, meet.jit.si, for immediate conference calls. They have now introduced a “Know Your Customer” policy and require at least one of the attendees to log in with a Facebook, Github (Microsoft), or Google account.
One option to avoid this is to self-host, but then you’ll be identifiable via your domain and have to maintain a server.
As a true alternative to Jitsi, there’s jami.net. It is a decentralized conference app, free open-source, and account creation is optional. It’s available for all major platforms (Mac, Windows, Linux, iOS, Android), including on F-Droid.
Safe to assume it was child porn, because that ends up being an issue on any service that lets people share images or video privately. By not stating it directly, they don’t prompt news organizations to quote the company in click bait articles about how their platform enables child porn as if that wasn’t a universal issue that all services have to actively discourage.