Multiple eff-ups appears to be the case:
https://www.cnn.com/2021/10/23/enter...day/index.html
"Three crew members who were on the set last weekend told the Times there were two accidental prop gun discharges before Thursday.
The rounds were accidentally fired October 16 by Baldwin's stunt double after he was told the gun was "cold," two of the crew members, who witnessed the discharges, told the newspaper."