SimpleX Chat is an instant messenger that is decentralized and doesn’t depend on any unique identifiers such as phone numbers or usernames. Users of SimpleX Chat can scan a QR code or click an invite link to participate in group conversations.
-privacyguides.org
It’s clearly proving to be the most innovative technology when it comes to decentralized communication, in my opinion.
Simple answer to the question so far as I can see: in order to connect with someone, you have to video conference with them and show them a code. So the anonymity is only as anonymous as the video conference you use to do that. All of the benefits it claims are merely an illusion.