Referenced the wrong discussion in the description. Here's the correct one:
godotengine/godot-proposals#9313

corrected description link as well.

This should be optional (defaulting to being disabled IMO), I personally don't want this feature enabled

The proposal references VSCode at the top, and the behavior there is definitely selecting. I personally took that to be more or less synonymous with "hilighting". Not sure a visual change that didn't scroll to it would be much use at all.

That makes sense, in the general terminology "highlighting" would mean something different that's what's was confusing

When changing scenes via quick open (Ctrl+Shift+O), the file does not get selected.

When changing scenes via quick open (Ctrl+Shift+O), the file does not get selected.

Looks like the signal for tab_changed is suppressed by this code here in EditorSceneTabs::_update_tab_titles()

int current_tab = EditorNode::get_editor_data().get_edited_scene();
if (scene_tabs->get_tab_count() > 0 && scene_tabs->get_current_tab() != current_tab) {
scene_tabs->set_block_signals(true);
scene_tabs->set_current_tab(current_tab);
scene_tabs->set_block_signals(false);
}

Not entirely sure if this is intentional? It seems to work correctly if I just remove the two block_signals calls.

Blocking the signal is intentional, as otherwise that method would get called again from the signal emitted from that method, potentially causing an infinite loop.
The EditorSceneTabs tab_changed signal is only intended to tell the EditorNode that a tab has been clicked via the tab bar, as the EditorNode is what handles the changing the scene. So this shouldn't use the signal, and instead be triggered from EditorNode::_set_current_scene_nocheck or somewhere.

I see!! thanks @kitbdev for the clarification.

Needs squashing.

Hey I believe I've squashed to 1 commit - could you double check just in case?

You can see at the top:

Not squashed.

See https://contributing.godotengine.org/en/latest/organization/pull_requests/creating_pull_requests.html#the-interactive-rebase

Thanks! Congratulations on your first merged contribution! 🎉