Right now when creating a Check Run only SHA is required meaning Check Runs are unique on per-SHA basis which can cause multiple problems when Check Runs also depend on a branch which I believe a pretty common use case.
For example, latest SHA on a release branch will always be the same as some SHA on your default branch.
Also if you have a different set of Check Runs for branch builds and PR builds then there is no way to delete Check Runs. You can have more Check Runs for a branch build and less for a PR build to do some basic testing, then once you create a PR from your branch you’ll end up with a mix of new Check Runs and old Check Runs.
Since a Check Run is associated with a Check Suite which has a unique id, it will be great to have an option to provide a branch or PR id when creating a Check Suite to deal with the issue on uniqueness of SHA in different branches/tags/etc.