Many people say that SimpleX is not ready to replace the likes of Whatsapp, Telegram and Signal yet but noone specifies exactly what features are missing.
I get that public key cryptography is confusing for the average people but there is no UI fix that is getting around that obstacle if we want people to make informed choices on what platform/protocol to use for communications.
The same thing applies to decentralization - people just need to understand that the trade-off they're making for communications' resilience is the comfort of an online addressbook.
Although I admit that there are certain UI elements that could be made better (for example the nickname setting could be stylized a bit better so people can more easily change the names of their contacts to something more familiar), most criticism towards SimpleX comes from people being a bit lazy and not reading the manual before using the app.
TL;DR: I don't understand what features are missing from SimpleX.
It appears that I was mistaken. After looking through Mullvad's documentation, it truly appears that it has really good fingerprinting protection.
The downsides I see with Mullvad Browser:
Sure, you could argue that these automatic connections are necessary and they are to trusted sites but you are still dealing with telemetry which should be disabled by default.
Nevertheless thank you for enlightening me. I will definetly now try out Mullvad Browser to replace Arkened Firefox.