[Bug]: Wrong active state in side navigation / table of contents

**Describe the bug**
On some of our pages / apps the side navigation / table of contents shows the wrong active state.

**To Reproduce**
On a page like CVEs there is a table of contents on the left. If you click on resources and then on description you can see that resources is still in active state, even though you clicked on description.
https://ubuntu.com/security/CVE-2025-21703

I have seen this issue in the 360 tool as well.

i am filing this here since it seems to be an issue we have in multiple site and apps. So it should probably be fixed at a DS level.

**Expected behavior**
The thing that is actually currently in view / what was clicked on is the active state in the table of contents / side navigation.

**Screenshots**

Start by reproducing the active-state behavior on the linked CVE page, then trace the side navigation or table-of-contents implementation in Vanilla Framework. Check the equivalent behavior in the 360 tool if available; done means the item currently in view or clicked is active consistently across the affected sites and apps.

Written by the indexing model from the issue text.