I hated zulip for the same thing, sad to hear the Rocketchat. So push notifications is only affecting mobile users or all users ?
Mobile users. And all their info is fuzzy. They've not exposed metrics to know what you use, and they keep saying you have to register but even putting in quite a bit of time to do so, I can't find any registration information. Their forums are full of people complaining that there is no transparency, the limits are BS, and nothing works. But that's all the info I can find.