Currently I'm located in Iran, and yes, many websites that depend on Firebase get automatically blocked (the same goes for medium.com). On top of that, many other websites decide not to provide service to Iran in the first place, so...

That's unfortunate. Also just a small clarification: I don't recommend disabling the "show-user-info-on-hover" feature, it's just there as an example :P

Maybe a stupid question, but why is the extension even talking to Firebase? Skimming the feature list, all of these look like something that should work without connecting anywhere else but HN itself.

The HN API is on Firebase, which is used to fetch details of users and items. It is used, as of now, in the following features:

  comments-ui-tweaks
  show-item-info-on-hover
  show-top-leaders-karma
  show-user-info-on-hover