Site Editor: editing a menu that appears in both Header and Footer autoscrolls the canvas to the other instance #82636

Description

When the same Menu (within a Navigation block) is placed in both the Header and the Footer template parts, editing an item in one instance causes the editor canvas to autoscroll to the other instance of the same navigation.

Observed with:

• Toggling Open in new tab on a Navigation Link inside the Header → canvas scrolls down to the Footer's copy of the same menu.
• Deleting a menu item from the Footer → canvas scrolls down to the Header's copy.
• The same in reverse: editing the Footer copy scrolls up to the Header copy.

The result is that after every edit, the user's view is thrown to a different part of the page and they have to scroll back to continue editing. In longer pages this is disorienting and easy to misinterpret as an editing failure ("did my change apply?").

Steps to reproduce

1. In the Site Editor, edit a template that includes both a Header template part and a Footer template part (or edit a page that includes both).
2. Add a Navigation block (containing the same custom menu) in both Header and the Footer .
3. Scroll to the Header. Select a menu item inside the Navigation block.
4. Toggle Open in new tab in the block settings (or delete the menu item).
5. Observe the canvas: focus / scroll position jumps to the same menu in the Footer.
6. Now do the reverse — edit a menu item in the Footer, observe the canvas jumping up to the Header.

Expected

Editing a menu item stays scrolled on the instance being edited — the user's viewport doesn't move.

Actual

After every edit, the canvas autoscrolls to the other template part containing the same Navigation block.

Environment

WP 7.1 - occurs both with and without Gutenberg active
Twenty Twenty Five