Note: This article refers to API versions 44 and higher. You will not see this problem analyzer if your target is on API v43 or earlier.
What triggers this problem analyzer?
If you've included Flow deletions in your deployment and those Flows are active in the target, this problem analyzer can be triggered.
What problem is it solving?
It's not possible to delete active Flows - you'll need to deactivate first. If you try to do this using the metadata API, your deployment will fail.
How does it work?
The analyzer will deactivate selected Flows and continue with the deployment of the deletion.