behavior of ASPNETCORE_Kestrel__Certificates__Default__Path in .net core 3.1

[alimhabib]

if I passed the HTTPS certificate following Microsoft steps ( include trust the certificate)

Hosting ASP.NET Core images with Docker over HTTPS I use mcr.microsoft.com/dotnet/aspnet:3.1-focal
using

• ASPNETCORE_ENVIRONMENT:Development
• ASPNETCORE_HTTPS_PORT:"8001"
• ASPNETCORE_URLS=https://+:443;http://+:80
• ASPNETCORE_Kestrel__Certificates__Default__Password:xxx
• ASPNETCORE_Kestrel__Certificates__Default__Path:

I always get an error

Unhandled exception. System.InvalidOperationException: Unable to configure HTTPS endpoint. No server certificate was specified, and the default developer certificate could not be found or is out of date.

it only works if I read the values and added them to

builder.UseKestrel()
                 
                .ConfigureKestrel(options => {
                    options.AddServerHeader = false;
                    if (isHttps) {
                        options.Listen(IPAddress.Loopback, DefaultPort, listenOptions => {
                            listenOptions.UseHttps(
                                 CertificateFilePath,
                                 CertificatePassword
                            );
                        });
                    }
                });

am a bit confused about the difference between the two approaches and when to use which, so it's the same certificate, same configurations but Ksterl never picks it up using only the environment variables. I don't have launchSettings.json in my docker image, is this the issue