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.
Tbf I’d not get angry if it was jihadist recruitment, child porn, human trafficking, etc. etc.
But won’t those criminals always find another way of communicating? If you’re doing something illegal, it’s worth it to you to go through some hoops to have safe and private communication. All this does is remove that option from less tech literate people.