Nix packages on a non-nix distro : what to do when a package isn't working properly ?

I hope this is the right place to ask. I am new to Nix and trying to use it for now as a universal package manager. I installled Stremio using Nix but the app doesn't work properly. I see that it's several versions out of date. The same app works fine using Flatpak. Is there a way to let the maintainer know? I'd also love some documentation that can help me update it myself. I can just use the Flatpak but I just want to have one less package manager to worry about.