DefaultNavHost prevents all fragments from moving back, how to disable the back button for one fragment?

Question

Android

I have 2 fragments, in the first one I select a list, in the second one I edit the selected list, how can I make it so that after exiting the second fragment into the first one, I could not press the back button, or I could but it would not return me to the previous fragment, did you just close the app? If I set defaultNavHost to false, then the back button is blocked in all fragments, and I need only in the very first, starting one.