You mean FTDs. More than likely they are FTDs. Rule 203b implemented many times with $DBMM, fill order before locate shares.
Billions of shares traded in 2014 and leading up to 2014 naked short shares were probably created. How many years prior~? Don't know. But up until 2017 billions more shares were traded. Plenty of FTDs and recycled shares brokers passed to one another.