Why i need to reconfigure environment variables when importing a managed solution from Dev to PROD

I have 2 environments:-

 

1) Dev

2) PROD

 

 

I usually do the following which was working well (last time i did an export/import was 3 weeks ago):-

 

1) Export the solution from Dev as managed solution

2) Import the solution to PROD using the Update option, as follow:-

 

 

where things will be straightforward, as all the environments variables inside the Dev, have the "Export" checkbox unchecked, so the environment variables inside the imported solution should use the setting inside PROD, without the need to reconfigure them, here is a sample of an environment variable inside Dev, where the "Export" checkbox is unchekced:-

 

 

but today i did the first export/import from 3 weeks ago , and when i import the solution inside PROD, i got that this connection need to be configured, which i usually do not receive:-

 

 

 

After that when i click on "Next", i were asked to reconfigure almost all the environment variables, as follow:-

 

 

 

so can anyone advice what is the issue? i defined the environment variables to not be used inside the solution by unchecking the "Export" checkbox

.. but why this is been ignored? and i were asked to reconfigure almost all the environment variables when importing the solution to PROD?