Tap the composer and type. The composer is the last in-flow row of a 100dvh shell, exactly like T3 Code's web client.

On iPadOS the keyboard shrinks only window.visualViewport; the layout viewport, this shell and everything anchored to its bottom stay where they are, so the composer, the / menu and the send button end up behind the keyboard.

On a desktop browser, press Simulate iPadOS keyboard for the same state (the platform behaviour is the only thing emulated here).