We have two parallel steps that run on every PR for repository:
On repository, I set up Slack chat notifications for "pipeline failed" and "pipeline fixed" to a particular channel, repository-wide. After pushing code to artificially trigger a pipeline failure, the notification appeared in Slack immediately after the pipeline failed. However, when pushing code to fix the failures, the pipeline completed but I did not receive a Slack notification.
I read the docs for chat notifications here, which describe "pipeline fixed" as "a successful completion after a failed attempt": https://confluence.atlassian.com/bitbucket/notifications-for-bitbucket-pipelines-857053284.html