Git branch is behind, but contains the same code after double merge

Question

For a project I've been working on we decided to work with a Git Flow oriented branching strategy, but were having some issues. Basically before every release, a branch is made from our develop branch to do some last minute bug fixes. This branch is eventually merged back into develop AND into master (master contains all our stable releases). Even though the code in our master branch is exactly the same as our develop branch (because the release branch is merged into both) GitLab says that our main branch is 30 ish commits behind develop. I'm guessing I don't fully comprehend the gist of git and merging branches, but I would like to know how to fix this... Any advice or tips are welcome!