There's a clearly stated description of the "coding error" from the middle of the article: The problem stemmed from two questions the CDC asks of states and ju

There's a clearly stated description of the "coding error" from the middle of the article: The problem stemmed from two questions the CDC asks of states and jurisdictions when they report fatalities, according to a source familiar with the issue. One data field asks if a person died “from illness/complications of illness,” and the field next to this asks for the date of death. When the answer is yes, then the date of death should be provided. But a problem apparently arose if a respondent included the date of death in this field even when the answer was “no” or “unknown”. The CDC’s system assumed that if a date was provided, then the “no” or “unknown” answer was an error, and the system switched the answer to “yes”. This resulted in an overcount of deaths due to Covid in the demographic breakdown, and the error, once discovered, was corrected last week.