connection string user name shown on exception page in production during sql connection error

I had no Microsoft Partner credits, so database got disabled. The sites did not show a decent error message, but a technical error showing my sql database user name. I do have trace on in the web.config, although this should not be related.

Ethical hackers see this as a security issue.

I don't think the 'standard' web.config would expose those details.  Did you change some settings?
See related topic
https://www.nopcommerce.com/en/boards/topic/82617/sqlexception-login-failed-for-user-

To my idea I did not change the code from the source github. It is the development config tag doing this. Thank you.

      <environmentVariables>
        <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Production" />
        <environmentVariable name="COMPLUS_ForceENC" value="1" />
      </environmentVariables>