I'm not familiar with GitHub Actions, but we reverted our migration to Bitbucket Pipelines because of a nasty side-effect of conditional execution: if a commit triggers test suite T1 but not T2, and T1 is successful, Bitbucket displays that commit with a green "everything is fine" check mark, regardless of the status of T2 on any ancestors of that commit.

That is, the green check mark means "the changes in this commit did not break anything that was not already broken", as opposed to the more useful "the repository, as of this commit, passes all tests".