Nginx default error page 400 has shown also when custom error pages is active

[StenoSanna]

We are using ingress-nginx (version 4.11.3 and controller image 1.11.3) as reverse-proxy frontend of our web application. With the custom-error-pages configuration we manage the error pages but we have an issue when the ingress tries to redirect errors to a named location during the early request processing phase when the request URI is not yet parsed. In this case the 400 default page has shown. Has someone met the same issue? How has it been resolved?? We have also tried to remove the "nginx" from the 400 standard page but there seems no way to do that. R Stefano