Why is this an issue?

Nested conditionals are hard to read and can make the order of operations complex to understand.

class Job:
    @property
    def readable_status(self):
        return "Running" if job.is_running else "Failed" if job.errors else "Succeeded"  # Noncompliant

Instead, use another line to express the nested operation in a separate statement.

class Job:
    @property
    def readable_status(self):
        if job.is_running:
            return "Running"
        return "Failed" if job.errors else "Succeeded"

Exceptions

No issue is raised on conditional expressions in comprehensions.

job_statuses = ["Running" if job.is_running else "Failed" if job.errors else "Succeeded" for job in jobs]  # Compliant by exception