Normally, if I were to close a tab while using a regular Firefox window, I could use the Ctrl+Shift+T hotkey to bring that tab back again. However, if I do so right now (for example, Wikipedia's Mozilla article), I will not bring that page back but instead an older, longer-closed tab from some days ago. I can keep trying to close and reopen tabs, or just keep reopening tabs, and I will continue to dig up older and older tabs from longer and longer ago.

Is this a known issue, what might have changed that behavior, and how do I restore the expected functionality of tabs correctly being reopened in the reverse order that they were closed?