Ask HN: What's the most frustrating user interface you use regularly?

I'm a university student working on a user interface design project. We're tasked with identifying and redesigning a problematic UI.

I'm curious about the pain points of a technical audience. What are the most frustrating websites, apps, or software interfaces you encounter in your daily work or life? What specific aspects make them bad? (e.g., poor layout, confusing navigation, lack of accessibility, etc.)