If you are still using the extension, a few things to clarify, some of which are addressed in recent versions.

"Close duplicates" keeps one tab. For 4 identical tabs, it closes 3 and keeps 1. The button was renamed from "Close all" to "Close duplicates" in v4.2.0, and the list now shows which tabs will be closed (strikethrough) versus which will be kept (full brightness), so the outcome should be predictable before you click.

Real-time list updates should work in the current version. Closing a tab via the X button triggers an immediate background update, and the list in the popup and options page refreshes automatically without needing a manual reload. If you are still seeing stale state after updating, please report it at https://github.com/Peuj/duplicate-tabs-closer/issues.

The current tab disappearing when navigating is expected behavior in auto-close mode: if you navigate to a URL already open in another tab, your current tab is the duplicate and gets closed. Setting "On duplicate tab detected" to "Do nothing" switches to manual mode, where nothing is closed automatically.

Space for the list: v4.2.0 adds a two-column popup layout with options and the duplicate list side by side, which gives more room to the list without needing to collapse settings manually.