Hi Bernard, Thanks for raising this issue - it certainly helped me! This after quite a number of hours trying to understand why zoom would not launch properly.
I agree with your suggestion that this should be a recommended dependency for firefox-esr. Although it would also make sense as a dependency for some of the KDE packages - I noticed that desktop-file-utils is listed as a dependency for gnome, mate, and cinnamon, but not for anything from KDE. Thanks again, Marten