What do you mean by what domain? If you mean the server it connects to, it’s in the screenshot.
As I said, this happens with a fresh install. I install from f-droid, I open the app and I get the connections to cloudfront.
So no extentions and no setup of any kind.
By googling I can tell this is an old problem. The solution reported in the last post of this thread doesn’t work in my case though.
It would be nice if the f-droid version would cone without these connections.
If it can be of any help, I’m on LTE. I haven’t tried on WIFI.