Just to confirm, is this the behaviour that you’re experiencing regardless of what events you selected the webhooks to be sending? You should be able to filter for specific events there:
I’ve left the settings as described in the Bitrise document for setting up the web hook. I need to know when a PR is updated, or created. I also need to know when a branch is pushed. I only really care about the source update though. According to the payload documentation, it sounds like Bitrise may only want to be checking for the source update in order to trigger a build.