spilloverRatio property

The value of the field must be in [0, 1].

When the ratio of the count of healthy backend endpoints in a zone to the count of backend endpoints in that same zone is equal to or above this threshold, the load balancer distributes new connections to all healthy endpoints in the local zone only. When the ratio of the count of healthy backend endpoints in a zone to the count of backend endpoints in that same zone is below this threshold, the load balancer distributes all new connections to all healthy endpoints across all zones.