After reboot of Intel Mac Pro Firefox no longer shows "top sites" in address bar

Hi there, I'm running the latest Firefox here on my trusty old Intel Mac Pro on Big Sur. Keeps on truckin'. However, just now I looked and the Mac said it had "Rebooted because of a problem". All my open tabs came right back up in Firefox and my Search History is fine. But when I click on the Address Bar I no longer get the list of top sites that I often visit, NY Times, banking, social media, etc. Why would that suddenly just disappear, and how can I get it back? Thanks for any tips! - Steve ''Moderator note: This question has been edited to correct the formatting.''