Can confirm that Mozillas review process is the most sofisticated i’ve ever experienced. The good thing is that when they have something to complain you have a competent person on the other side that really helps you. Not like Apple who only send you some boilerplate to all your responses. The downside at Mozilla is that it takes them ages to even start the review, it took me once over 2 month to get my extension in their catalog.
Why do they allow so many extensions that rely on third-party services though? I don't like this trend. Especially given there's no network sandboxing of any sort, giving permissions for an extension to access your data locally is very different from allowing it to send them to a third-part, untrusted server.