On the surface, the new FBI crime report for 2021 makes it look like homicides plummeted. In reality, a large number of law enforcement agencies, including the NYPD, just stopped participating.
Normally, only very tiny law enforcement agencies are missing.
In 2020, 82.3% of all law enforcement agencies in the USA were providing data. In 2021, only 62.7% cooperated.
New York has 595 law enforcement agencies. In 2020, 94.6% participated. In 2021, it was only 20.9%.
California has 740 law enforcement agencies. In 2020, 98.9% cooperated. In 2021, it was only 2%.
The FBI instituted a new data collection system. Instead of switching over, many thousands of police departments simply stopped participating. For California, nearly every single law enforcement agency in the state stopped participating.