It has become less secure due to a technique called MFA fatigue where the attacker repeatedly attempts to sign into your account. Each time a yes/no prompt is sent to your device. After a few dozen notifications the user may accidentally hit Yes. This is the exact technique a hacker used to completely own Uber last year. In response to the Uber hack, Microsoft now forces users to enter the random 2-digit number that arrives with the notification, in addition to accepting the yes/no prompt. This, of course, defeats the original purpose of the convenience of just tapping Yes on your phone vs. typing in a random code. (Or just tapping Yes on your watch, which I really miss.) The prompt will eventually become even more secure with a future update by displaying additional information, such as the geographic location the sign-in request is coming from. Maybe you share your login with someone else and you want to accept the prompt to help them get signed in, but why is this request coming from Madagascar? You get the idea. But this is only what Microsoft is doing with their push notification MFA. The original push notification MFA company, DUO, has not changed anything and is still susceptible to the MFA fatigue attack.