The Izzy repo may be popular but with getting more than 1000 apps in that repo which are also in the main F-Droid repo I've been hesitant to add it. What happens when Izzy repo has a newer version than the F-Droid repo ? The main F-Droid repo goes for reproducible builds and checks for closed source software and more. Izzy repo downloads from the app upstream, does a malware check and that is all it seems.