I was cleaning up the UI on a side-project iOS app and did one thing: set Dynamic Type to XXXL and screenshot every screen.

Reading the code had turned up nothing. The screenshots showed problems immediately.

Eleven of them, in the end. All the same cause.

Here's the conclusion first. "A parent that pins things side by side" × "text that grows" is not a bug, it's a pattern. And in Japanese it breaks reliably worse than in English.

English truncates. Japanese stacks vertically.