To get the HPAs managed by particular ScaledObject, find first the value assigned to scaledobject.keda.sh/name to the ScaledObject, then use that to select the HPAs. This is because this label is applied to both the ScaledObject and the HPAs it manages.
k get hpa -l scaledobject.keda.sh/name=ai-worker
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
keda-hpa-ai-worker Deployment/ai-worker <unknown>/5 (avg) 1 10 0 23m
Reference: https://keda.sh/docs/2.20/concepts/admission-webhooks/