It seems that when using gerrit-plugin in combination with multibranch-pipelines, we get all discovered branches as normal branches instead of having them split between real-branches and temporary ones (pull-requests).
I am attaching screenshots of a sample github repository and a gerrit sample repository, so it is clearly visible that multibranch-pipeline does treat CRs as branches instead of PRs (they are not displayed in their separated tab).
This is also likely to affect the Blue Ocean gui too and it may be a real deal for users that do have lots of production branches and open pull requests. I know for sure that having 5-10 production branches and 5-50 open CRs is not uncommon.
Another issue spotted here is that the patchset version is included in the branch name, which is a real issue because it means that a Jenkins will create a new temporary branch for each updated changeset, instead of using a single one with multiple builds. Having the build history in one place is key as it allows users (and reviewers) to see how execution changed in time.