Related horizontal safe area issue on iOS 26+: a standalone UIToolbar shifts its items too far right when the left safe area inset comes from the view controller (additionalSafeAreaInsets / iPhone Duo vertical bar). Filed as FB25095941 with a sample project.

Possibly the same root cause, seen from UIKit: a standalone UIToolbar gets extra leading padding when its left safe area inset comes from the view controller (additionalSafeAreaInsets.left, or the iPhone Duo vertical bar on the left). With a left inset of 84 pt the first item lands at ~200 pt instead of ~105 pt. The same inset on the right is handled correctly, and so is a window-level inset (Dynamic Island side in landscape). Reproduces on iOS 26.5, 27.0 and 27.1 (Simulator and an iPhone 17 Pro Max), not on iOS 17.5 / 18.6. Pinning the toolbar to safeAreaLayoutGuide instead of the view's edges works around it. Filed as FB25095941 with a sample project.