The title is clickbait. Both "welcome back" and "Sign In" show the blue outline around the field and safari asks the user to select a username in the dropdown

The title is clickbait. Both "welcome back" and "Sign In" show the blue outline around the field and safari asks the user to select a username in the dropdown without actually filling the field. The user needs to actively click on the username for safari to fill the field. I don't see how this is "bad behaviour". Seems like expected behaviour.