The most obvious situation is that, with the theme parks closed, there’s simply a surplus of the bottles, and so the decision was made to sell them at retail rather than let them go to waste.
At this point, it looks like the Cokes have only been found in this one store.
Certainly, the bottles have a limited shelf life so at some point they will go bad.
There’s a number of theories about how this store could have ended up with some of the bottles .