The test that was meant to assert this being right was broken and is getting fixed by #34368

Unfortunatey, it turns out that the a11y traversal ordering thinks that the actions should come ahead of the back button and search field.

This can be easily reproduced in the Flutter Gallery demo - navigate to that page with a11y turned off, then turn it on. Swipe right to start navigating, and the first thing that gets landed on is Voice Search rather than Back (or Search).