How does the Build's commit inclusion logic work?

I have a question about how TeamCity attaches git commits to a build.  See the attached image (I've removed some details for privacy) which shows the Change Log for a build configuration.  The config uses feature branching with github as the VCS:

- The build # is a custom label (#9.3.919-2c0fedb)
- The different links are from an integration plugin with JIRA
- We have our main "master" branch with some other related branches in the left blue lane, and some other branches ("kanban" among others) in the right blue lane

My question is: why does build #9.3.919-2c0fedb include any commits other than the "Merge branch 'release/R9.3'" commit?  Why does the "Merge branch 'feature/...577' into kanban" commit (as well as its children commits) get included too?  It's confusing to me because the branches don't get merged back together.

Does this make sense?