A few months ago, X changed their two-factor authentication feature by limiting the option of using SMS to X Premium customers. Without SMS, users are forced to turn to apps like Google Authenticator or use physical security keys.
Most recently, X is reportedly testing the passkey feature, a new login method without the need for a password. The use of passkey also depends on the device used and also the software running.
Passkey is a technology that Apple, Google and Microsoft work together. It supports the FIDO Alliance standard to simplify the login process. The iPhone for example can use Face ID or Touch ID to verify the user's identity before logging in. Google on the other hand with a fingerprint scan or QR code.
At the moment it is still uncertain when X will start offering the use of this passkey. In my experiments with Google accounts so far, it's the thing that makes my life so much easier now.