I'm aware, and why I stated "Costco in the USA". I regularly visit Costcos in British Columbia, Canada. Fortunately no other major battery retailer in the USA has followed suit, after two years. No one can predict the future...but we haven't seen any other battery retailer follow.
Perhaps Costco shoppers are different than WalMart shoppers?
They aren't but no demographic is immune from doing questionable things.
Two years have passed, but that's no assurance.
The industry has shifted, and will continue to shift, over time.
Long prorated warranties used to be marketed as an indicator of durability, and assurance; they have largely disappeared. The boast of a 60-84 month warranty sounded attractive, but they paid peanuts in the end. No big loss.
What remained are the replacement warranties. AFAIK, most are in the 2-4 year range; I haven't come across one from a common brand that's longer. Costco was one of the bigger brands to eliminate them first.
Walmart covers all their bases, segmenting the market for coverage in budget/good/better/best ranging from 1-4 years.
In the current business climate of uncertainty, and reduced confidence, even profitable companies are having layoffs to burnish their books, including Walmart.
A product like a vehicle battery is less elastic in demand; they're often purchased under duress, not choice, and people don't have the option of not buying a battery just because it rose by $10, or its warranty is worse. Food producers take full advantage of this, and you end up with things like shrinkflation, or "frozen dairy dessert" instead of ice cream.
They have the room to play, and test the limits. Not to say they will, or will not, but the option is there, and every large company will have the staff do that analysis, and make changes, whether in warranty terms, ingredient content, package sizes, etc.
We've seen that repeatedly and if would be foolish to expect that car batteries would not come under scrutiny as well.