QuotaExceeded

Which enforced limit a node is refusing work over, per resource, because they are freed by different actions: disk by deleting or optimizing, memory by unloading.

A flag outlasts the reading that set it. A resource that reaches its limit stays flagged until it has fallen a margin below, so expect to see one set while the reported utilization is already back under the limit. Null is not false: it means the node is not enforcing that resource at all, and reporting it as within its limits would invite an alert that can never fire.