Comment by AdmiralAsshat

"Close Duplicate Tabs" is actually a really useful feature for some. My Firefox at work has dozens of tabs open at any given moment, mostly JIRA tickets, and it's very easy to have the same issue open in three different tabs when I'm constantly opening links from email, Teams, etc. I had looked into installing an extension to get similar functionality, but held off. I'm glad it's now baked into the software.