I never trust “once” fired brass from any one selling it wholesale, never.
Starting out, get yourself new. Then you can trace the history of your cases. Glocks are hard on cases, harder than most guns from case bulging. I limit the number of times I reload the same case in Glocks I also keep them separate.
It’s cheap at 36$ per 1000 VS 124$ from Starline but you also need to factor in the cleaning and work to get them to same as new condition.
Also from the looks of the photo, some have a considerable amount of corrosion.
"The difference between stupidity and genius is that genius has its limits" Albert Einstine