When using PDBs with MaxUnavailable or MinAvailable (percentage), it is not supported to reference pods via a PDB selector, that do not have a supported controller owner reference:

Nevertheless, there are still people who create PDBs a pods without controllers that ignore this. For example PDBs that set MaxUnavailable: 0, want to block eviction, and node drain (it works for them but the PDB status is invalid).

Unfortunately there is no feedback for the user to receive when this happens. The KCM logs is the only place that informs the user when unmanaged pods are found.