Perhaps the Committee on Publication Ethics might include in its guidelines:
When an article is retracted, publishers should notify authors of all papers which have cited it.
Matt Berkley
Whereas retractions usually expose scandals in science, citations to retracted articles are a bigger scandal, especially when they are post-retraction.
XeraRetractions web app: openscience.xera.ac/retractions
Discover which papers cite retracted research. Comprehensive database updated daily with Retraction Watch data. Essential tool for research integrity.