Huh, you’re the first person I’ve encountered liking that behaviour. Since Firefox switched to MRU Ctrl+Tab by default,
every Firefox user I know (whether a long-time user, one migrating from another browser, or someone for whom it is their first browser by virtue of their youth, and I have at least one in each category) has successfully found and toggled that option.
I must admit, however, that I do have Tab Flip for Tree Style Tab, with Shift+F2 to switch between the current and most recently selected tabs (like Ctrl+6 in Vim to toggle between the most recent buffers), and have added similar elsewhere, with Meta+F2 to switch between most recent workspaces in the Sway or i3 window managers:
bindsym Mod4+F2 workspace back_and_forth
bindsym Mod4+Shift+F2 move container to workspace back_and_forth, workspace back_and_forth
I wouldn’t want to be without at least this single-level MRU in my browser or window manager. (On more traditional window managers, you normally have Alt+Tab or ⌘⇥ and ⌘` which are all some form of more extensive MRU list, though I find macOS’s application-level treatment bizarre and extraordinarily frustrating because of how cripplingly limiting it is if you work with multiple multi-window apps and want to see a window of each. And yeah, it’s easy to see when reflecting on Alt+Tab why Firefox went the way they did with Ctrl+Tab, making it behave similarly. But I haven’t previously found anyone actually liking it.)