As far as I understand there are two or more helm repos with nginx-ingress.
nginx-stable > https://helm.nginx.com/stable
ingress-nginx > https://kubernetes.github.io/ingress-nginx
Firstly I have installed from nginx-stable, but this installation by default use selfsigned certs. When I try to investigate this question I have found out that in official tutorial https://kubernetes.github.io/ingress-nginx/deploy/ (which address is very similar to ingress-nginx helm repo) gives another repo https://helm.nginx.com/stable When I have tried to generate helm templates for both these repos, I found out that result is different. Could anyone explain why there are two repos, and what distinguish between them