This happens when the feature to show password text is inadvertently activated, as can happen when keyboard mashing to wake device. Details in link by Alex in comment 7.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1772791 Title: Lock/login screen displays password in clear text occasionally To manage notifications about this bug go to: https://bugs.launchpad.net/gnome-shell/+bug/1772791/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
