I am seeing a lot of Urban gas pump Legends, of non factually threats.
For example,
the ozone release theory . just plain stupid
the dreaded fill up after the gas station finally got some fresh volatile gas in is forgetting one thing. They filter the gas before it leaves the pump.
You would want to use the slowest gas flow setting so the gas is not frothed up taking up valuable gas tank space and has absolutely nothing to do with gas evaporating on its way down the filler neck.
The extra gas that one might put in after the pump has filled and shut off would not evaporate. Gasoline cars have a sealed gas system, meaning the tank will not evaporate any fuel you put in it.
Some people fill up the gas tank until they see gas in the filler neck
and make that the mark to fill too.
If you use the same gas stall every time you will always get the same reading from the filler neck as the ground may or may not be level at different gas pumps and stations.
Oh and welcome to the forum !