Previously, when unschedulable Pods are updated, the scheduler always put Pods back to activeQ/backoffQ. But, actually not all updates to Pods make Pods schedulable, especially considering many scheduling constraints nowadays are immutable.

- QueueingHint implementation for NodeUnschedulable is reverted because we found potential scenarios where events that make Pods schedulable could be missed. ([#122288](https://github.com/kubernetes/kubernetes/pull/122288), [@sanposhiho](...

- QueueingHint implementation for NodeUnschedulable is reverted because we found potential scenarios where events that make Pods schedulable could be missed. ([#122326](https://github.com/kubernetes/kubernetes/pull/122326), [@sanposhiho](...

    `--enforce-node-allocatable=””`
  * Hard Eviction Thresholds will be subtracted from Capacity while calculating
    Node Allocatable. This will result in a reduction of schedulable capacity in
    clusters post upgrade where kubelet hard eviction has been turned on for
    memory. To opt-out set `--experimental-allocatable-ignore-eviction=true`.
  * More details on these feature here:

* scheduler: use incremental scheduling cycle in PriorityQueue to put all in-flight unschedulable pods back to active queue if we received move request ([#73309](https://github.com/kubernetes/kubernetes/pull/73309), [@cofyc](https://github.com/cofyc))

- Improved scheduler robustness to ensure that unschedulable pods are reconsidered for scheduling when appropriate. ([#73700](https://github.com/kubernetes/kubernetes/pull/73700), [#72558](https://github.com/kubernetes/kubernetes/pull/72558), [@denkensk](https://github.com/denkensk), [#73078](https://gi...

* add goroutine to move unschedulable pods to activeq if they are not retried for more than 1 minute ([#72558](https://github.com/kubernetes/kubernetes/pull/72558), [@denkensk](https://github.com/denkensk))

### Other notable changes

* Scheduler only activates unschedulable pods if node's scheduling related properties change. ([#71551](https://github.com/kubernetes/kubernetes/pull/71551), [@mlmhl](https://github.com/mlmhl))
* Disable proxy to loopback and linklocal ([#71980](https://github.com/kubernetes/kubernetes/pull/71980), [@micahhausler](https://github.com/micahhausler))

- Sometimes, the scheduler incorrectly placed a pod in the "unschedulable" queue instead of the "backoff" queue. This happened when some plugin previously declared the pod as "unschedulable" and then in a later attempt encounters some other error. Scheduling of that pod then got delayed by up to five minutes, after which periodic flushing moved the pod back into the "active"...

- Sometimes, the scheduler incorrectly placed a pod in the "unschedulable" queue instead of the "backoff" queue. This happened when some plugin previously declared the pod as "unschedulable" and then in a later attempt encounters some other error. Scheduling of that pod then got delayed by up to five minutes, after which periodic flushing moved the pod back into the "active"...