(Feel free to update this bug's summary to be more specific.)
Component Readiness has found a potential regression in the following test:

[sig-network][endpoints] admission [apigroup:config.openshift.io] blocks manual creation of EndpointSlices pointing to the cluster or service network [Suite:openshift/conformance/parallel]

Significant regression detected.
Fishers Exact probability of a regression: 99.99%.
Test pass rate dropped from 100.00% to 91.43%.

Sample (being evaluated) Release: 4.20
Start Time: 2025-08-12T00:00:00Z
End Time: 2025-08-19T16:00:00Z
Success Rate: 91.43%
Successes: 32
Failures: 3
Flakes: 0
Base (historical) Release: 4.19
Start Time: 2025-05-18T00:00:00Z
End Time: 2025-06-17T23:59:59Z
Success Rate: 100.00%
Successes: 112
Failures: 0
Flakes: 0

View the test details report for additional context.

Slack thread: https://redhat-internal.slack.com/archives/C07QEA1PDFX/p1755619758460629

Payload and release blocker so super critical. Team has identified https://github.com/openshift/managed-cluster-validating-webhooks/commit/3fb8935719704801fdeeed9da2941db9218fb572 as likely culprit.

Filed by: dgoodwin@redhat.com