Statically generated WordPress include index.html in each URL

I have statically generated WordPress website (with plugin called Staatic). I used option Offline Usage which recommends to make static content to be run on local machine and static web hosting. But after I visit web root index.html and other index.html files (which are under directories with names of web pages), everytime it includes index.html at the end of each URL.

with index.html —> https://domain.com/index.html , https://domain.com/page-name-here/index.html

What I want is to remove /index.html at the each file URL. So it looks;

https://domain.com/page-name-here/index.html

WordPress is running on NGINX. WordPress, plugins are updated.

Any help to solve this issue would be appreciated.