the ruleIf the number moved the same way for everybody, something real may have happened. If it moved in both directions depending on how the subject is composed, it is definitionally a remapping, and any model predicting a real-world change at that boundary has confused the map with the territory.
Day-one CECL effects for 1 January 2020, from each bank's Q1 2020 Form 10-Q. The contrast series is simulated and labelled as such.