When does Unique UI become Bad UI?

I’ve been reading up on Mental Model Mismatches—that frustrating moment when a website tries to be so "unique" that you can't even find the login button or the search bar.

As we build out projects and platforms, there’s always a temptation to do something "never seen before." But HCI principles suggest that breaking established patterns usually just leads to high bounce rates.

I want to hear from the tech enthusiasts here:

• What is the most frustrating "unique" UI choice you've encountered recently?
• Is there a specific convention (like the 'hamburger' menu) that you think is actually ready to be reinvented, or should we stay "standard" forever?

I've posted a full breakdown on the blog about how these mismatches hurt retention.

Let's debate: Innovation vs. Familiarity—where do you draw the line?