While Chromium continuously gets updates on Leap v74.0, v75.0, v76.0, v77.0, etc. on the Main Update Repository, FireFox is stuck on the old v60. The latest FireFox version is 69.
It is very important to have the latest stable Web Browser.
I understand that Leap should have more stable packages than Tumbleweed, but it should not have such an old browser.
Leap 15.1 came with Chromium 74.0.3729. Instead of remaining on version 74 and only get specific patch updates, it has been regularly updated to new major versions.
There is an additional Mozilla repository for Leap, but it looks like it is perhaps invalid (Show 7 excluded/disabled results)
https://download.opensuse.org/repositories/mozilla/openSUSE_Leap_15.1/
An Web application we develop experienced problems, a certain page not working properly with FireFox 60, but worked fine in FireFox 69.