http://isdb4l77sjqoy2qq7ipum6x3at6hyn3jmxfx4zdhc72ufbmuq4ilwkqd.onion/blog/20220901-simplex-chat-v3.2-incognito-mode.html
SimpleX objective is to provide anonymity from the network operators, but not necessarily from your contacts. even if you choose a pseudonym, it would be used for all your contacts. And if two of them meet, while they cannot prove they are talking to the same person, as they use different addresses in SimpleX network to send you the messages, they could suspect it . any pseudonym you manually choose leaks some information about you, as it's not really random.