Under the hood
Fast mode's setting sync now behaves differently while a background auto-mode setup is still running
What
When background auto-mode setup is in progress, Fast mode's settings-sync logic no longer takes its usual early exit, and instead forces the Fast-mode toggle to apply only to the current session rather than being saved more broadly.
Why
This avoids Fast mode's setting sync racing with an in-progress auto-mode setup, keeping the toggle scoped to the current session until that setup finishes.