Earlier quoted context omitted.
> Both services are relatively insecure because they require phone authentication. That hasn't been the case for Signal for some months: https://signal.org/blog/phone-number-privacy-usernames/ You still require a phone number for sign up for Signal, but your phone number isn't visible to anyone you chat with.
> but your phone number isn't visible to anyone you chat with. That's irrelevant - the phone number is known to Signal and can be request by law enforcement. And, since it's been made pretty much impossible to buy a SIM in the EU without showing identification [0], this will allow law enforcement to link the account to you. [0] IIRC the Netherlands is the only country left where you can buy SIMs without ID.
As far as I know, in Romania you can still buy and activate a prepaid SIM card without having to show your ID. There was an attempt a few years ago to make it mandatory to tie the phone number to an ID, but it was overruled by the Constitutional Court.