This is probably my favourite feature of Firefox, and it's not available in Chrome/Edge!
It enables a tab switcher UI when using Ctrl+Tab, with tabs in most recently used order. Just like Alt+Tab in Windows.
The default behaviour (like Chrome/Edge) is for Ctrl + Tab cycling through tabs in the order they appear on screen, with no tab previews.
I figure that anyone (power users) who uses Ctrl+Tab for navigating tabs would be happy to see this enabled, and may not know the option exists.
Out of the box, the setting isn't enabled. Hopefully it can be turned on by default!