Must have been a GM thing..............
Had an older Volvo backfire at a light, the fuel lines were not fireproof...electric fuel pumps, pump without the engine running! LOTS!
Not an unusual occurrence.
Happens all over France, all the time?
When I was a small child, early 60’s, I remember my uncles, then in their 20’s, were doing something like turning the ignition off and back on again while going slow that would cause a backfire on their 40’s and 50’s era automobiles.............