Azure DevOps Repos, situation is really simple, we have
After some commit on Develop, we create pull request from Develop > To Master and it completing without conflicts and all change are merged into Master. All is ok.
But now, on Azure DevOps Develop seems is 1 commit behind respect to Master, but from git command line all is up-to-date.
Why?
Thanks in advantage
The merge will add a special kind of commit which combines the 2 branches together; The head of your master and develop branch. It allows you to merge branches even when both branches have 'new' commits (which are not part of the history of the other branch).
There's also a fast-forward merge (think it's called rebase in azure devops) that does what you're expecting where it simply pastes the new commits onto the master in a linear fashion without the additional commit. But it requires the your develop branch to be up to date with the master.
It's a preference, but having the merge commit gives you some extra insights when it was merged and all related information provided by the platform. E.g. for azure devops it'll link work items and the pull request to it in their UI.