MSSQL username and password ( variable env) but when export / import, these are lost
That is a security feature. Any/all nodes that use the node-red credentials do this. I realise that it is inconvenient when the password is an ENV VAR (instead of an actual password) but that is how the credentials currently work.
You could open a feature request thread in #development:feature-requests and see if it gets traction?
Example of what? Starting a new thread? Just do what you did to start this thread, explain your issue, ask about the feasibility of exporting credentials when they are ENV VARs instead of a username/password