I think my oldest current tab is from last June, because I actually cleared all my tabs in spring 2020 when I had nothing else to do! And since then J've been trying to remember that bookmarks are a thing and I don't actually have to leave the tabs open, so I was doing pretty good up until yuletide. Right now I only have 18 non-yt tabs open.

(Also it's possible to save a session and restore in on a different device/after a wipe, so I have sometimes kept the same tabs open even past that.)