User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:76.0) Gecko/20100101 Firefox/76.0

Steps to reproduce:

Reopen a closed tab (keyboard shortcut ctrl+shift+t).

Actual results:

The reopened tab does not display the last page visited in that tab. It actually shows the first page visited from that tab when it was originally opened, and pressing the back button brings you to the last page visited. Essentially, the oldest element in the history for that tab is duplicated to be the most recent element (and current page).

Expected results:

The most recently visited page should be reopened.

It appears that this issue only happens when an extension is modifying the new tab page. I have reproduced the issue with multiple extensions and therefore is not a bug with an individual extension.

This issue seems to be a duplicate of Bug 1627801 so I'm going to mark it accordingly.
Thank you for reporting!