Same issue on my iPhone running the latest 18.4. It is showing a tab from my iPad, also running the latest 18.4, even though it hasn’t been open for awhile. And whenever I delete it, it reappears as soon as I go back into Safari on the iPad.
It does however make a change for iCloud tab syncing to be finally working somewhat again because Apple, along with most everything else, have royally screwed this up.