Firefox devtools where long time not comparable to chrome, now they are almost the same.
There are now some features I prefer on Firefox and some I prefer on chrome.
The biggest difference was Firefox's best Dev Tools in those years were extensions and maintained via a wider community and updated on a different (sometimes faster) cadence than the browser itself. Good old Firebug was more capable than Chrome's Dev Tools at most points in time in that "long time not comparable" people believe existed, but Firefox didn't get "credit" for it until Firefox was finally pressured to move extensions like Firebug in-box and into the browser's normal deployment cycle. (I'm not sure that's necessarily the improvement people think it was.)