Guidelines for maintenance branch

[claf]

I've seen some discussion related to questions I have (for instance here #526) but I still struggle figuring out the "right" way to do some of the following :

Let's say you have released a version 1 or your product and are actively working of version 2. Version 1 sits in a maintenance branch while version 2 is in the main/master branch and not released yet.

Two scenarios I'm interested to discuss here :

1. A bug is found in version 1 but is not present in version 2, you produce a version 1.1 to fix the issue. changelog of version 1.1 contains this fix, but what about changelog in version 2? do you report it for "history" or do you consider it's not relevant since version 2 is not impacted?

2. A bug is found in version 1 and is present in version 2. You produce a version 1.1 to fix the issue and you port this fix to version 2 / main/master branch. Do the changelog in both branch state the same thing ? Or is the bug fixed under v1.1 for the 1.1 release and fixed under v2.0 for the 2.0 future release?!