If DeVonta Smith’s helmet stays on?

The ball was OUT with no whistle so In My Humble Opinion ( which I realize counts for nothing) it was a fumble and SAINTS recovery~! Sorry for the kid from Amite, LA but no one really explained why it wasn't that I heard and I was listening to WWL's broadcast~! Does ANYONE really KNOW what happened that play and would like to share? Pivotal point in the game I'd say...........