The Focus feature has nothing to do with sharing your account.
Set up a Focus on iPhone - Apple Support
"Focus is a feature that helps you concentrate on a task by minimizing distractions. When you want to concentrate on a specific activity, you can customize one of the provided Focus options—for example Work, Personal, or Sleep—or create a custom Focus. mYou can use Focus to temporarily silence all notifications, or allow only specific notifications—ones that apply to your task, for example—and let other people and apps know you’re busy."
If you are sharing your Apple Account with someone else, you should stop.