Yes the original authors are Mozilla, but some F-Droid users/staff are responsible for Fennec.
They point to the official Mozilla Bugzilla. They won’t change any default search provider upstream. I could not find either any responsible person for Fennec or an official source repository or issue tracker for Fennec so far.
Don’t get me wrong @Licaon_Kter , I was just referring to this:
and I stated that this is nothing the original upstream developers from Mozilla would change.
If I understand it correctly, the aim of Fennec is “only” to deliver a build which is free from proprietary dependencies/other stuff, isn’t it? Otherwise I would also have a small improvement idea for reducing anti features. But I understand you have more important this to do and Fennec has an uncertain future because of Fenix as well.