How to remove Firebase dependencies from open-source app Tachiyomi J2K?

I'm slowly trying to remove my dependency (pun intended) from Google as much as possible.

One of the open-source apps I heavily use is Tachiyomi J2K but it has Firebase dependencies.

The developer previously closed down someone elses' request for the same. So thought I should at least give it a try but upon searching couldn't find a proper guide.

I have no coding experience but really would appreciate if someone could help.

Thanks

app dependencies firebase privacy