I am wondering if there could be two classes of apps that are built by build-servers.
(i.e) lets say priority apps: like NewPipe (may be Öffi) are checked and built every few hours.
Though one may feel why a ‘non-free’ service like youtube’s app - needs priority - life is unfair. More people use it - especially for those average user.
Not sure (due to being clean) if fdroid-servers have a list of most downloaded apps.