What happens when we advance the project

Hi, I was asked to build and deploy a PY package. The project status was 21. I tried to advance the project to status 26 so that I can assemble a package. But during advancement to 26 (from 21), I got the error message of token inheritance and then the status was automatically rolled back to 21.

I build and deployed the PY package while the project status was still 21.

Now questions:

1. What happen when we advance the project from 21 to 26

2. Can we build and deploy the project without advancing the project

3. In my case, what happened in my case when I build and deployed the PY package with status 21, the deployment and build was successful. Have we missed anything