Microsoft is trying to protect customers from malware and phishing attacks, with a warning in Windows 11 when copying and pasting your password.
Microsoft revealed the new feature in a blog post:
Starting in Windows 11, version 22H2, Enhanced Phishing Protection in Microsoft Defender SmartScreen helps protect Microsoft school or work passwords against phishing and unsafe usage on sites and apps. We are trying out a change starting with this build where users who have enabled warning options for Windows Security under App & browser control > Reputation-based protection > Phishing protection will see a UI warning on unsafe password copy and paste, just as they currently see when they type in their password.
It remains to be seen if this feature will make a measurable difference, or if people will simply disable it.