So, I have a bad habit of keeping pages open in my browser and letting them accumulate in order to read them at a later date. Bad habit, I know. But, when going through and closing old tabs I no longer need, I noticed that the undo close tab button doesn't actually undo the tab you just closed. Instead of re-opening the tab you most recently closed, it re-opens whichever tab you closed recently which most recently *opened*. For example - say I have seven tabs open, with tab one being on the left/opened first, and tab seven being on the right/opened most recently. If I close tab seven and then close tab two, and then I click the undo close tab button, tab seven will be the one to be re-opened, even though it was closed before I closed tab two. Likewise, the tabs on the far left won't show up under recently closed tabs if there are tabs further to the right that were closed, even if they were closed before the tabs on the left.

I discovered this while clearing out tabs I had open. I closed several tabs on the right/most-recent, and then went to the left/oldest tabs and started closing those. I realized after opening a tab that I still kind of needed that page for other things. However, when I went to undo close tab, the tab that opened wasn't the tab I had just closed, it was one of the tabs I had closed several minutes prior that were on the right/most-recent side of the page. The tab which I closed on accident was nowhere to be found in my history.