If you'd ever supplied a phone number as a backup-auth, then a SIM/phone-number-hijack would be a likely cause. (I think you'd see an email about a password reset in that case.)
But also any 3rd-party app that was ever granted posting access ª then itself compromised or misused – could also be to blame.
And of course the fact that any "suspicious" activity (even just a bouncy internet connection, in my experience) triggers a phone-number demand may solve some of Twitter's problems, while making things worse for the user, revealing to Twitter extra personal-info that:
• leaves you at risk of future phone-number-based account hijacks
Interesting! But: I never gave Twitter my phone number exactly because I figured that that would open me up to SIM swap attacks and the password on the account is quite secure. As secure as this machine, I guess.
If you'd ever supplied a phone number as a backup-auth, then a SIM/phone-number-hijack would be a likely cause. (I think you'd see an email about a password reset in that case.)
But also any 3rd-party app that was ever granted posting access ª then itself compromised or misused – could also be to blame.
And of course the fact that any "suspicious" activity (even just a bouncy internet connection, in my experience) triggers a phone-number demand may solve some of Twitter's problems, while making things worse for the user, revealing to Twitter extra personal-info that:
• leaves you at risk of future phone-number-based account hijacks
• has on at least once occasion been abused by Twitter employees, secretly working for oppressive regimes, to target regime critics: https://www.nytimes.com/2019/11/06/technology/twitter-saudi-...
• has previously been leaked through a sketchy 3rd-party SMS provider to governments & law-enforcement & who-knows-who-else without Twitter even knowing: https://9to5mac.com/2022/02/09/twitter-2fa-text-privacy/
• has been used by Twitter for marketing purposes beyond the initial authorization purpose: https://www.washingtonpost.com/technology/2019/10/08/twitter...