Matthew GarrettTwitter's new encrypted DM system stores your private key material on Twitter-owned services, protected with nothing more than a 4-digit PIN. If hostile, or if legally compelled to, Twitter could easily decrypt all your messages. It's also MITMable and doesn't secure metadata. Use Signal.
Shredd Tone 
@mjg59 I recall Musk in an interview stating the he was shocked to find that companies and authorities could access users DM's so easily and wants to implement encryption for private messaging.
Now the question is: how surprised do you think he'll be if they could all still be able to access users messages?