with https://amd64.ocp.releases.ci.openshift.org/releasestream/4.20.0-0.nightly/release/4.20.0-0.nightly-2025-05-29-181045 we started seeing failures of

[sig-architecture] Conformance Tests should have at least two untainted nodes [Conformance] [Suite:openshift/conformance/parallel/minimal] [Suite:k8s] 

... which is clearly not expected to run on single-node or microshift. The culprit appears to be https://github.com/openshift/kubernetes/pull/2299
Other tests could have been missed and may be affected as well, but the failures for this one were evident.