Popcorn can be a choking hazard, and the added butter and salt can be harmful to cats' health.
Popcorn is mostly carbohydrates, which cats do not need, and regular consumption can lead to obesity and diabetes.
Raw popcorn kernels are difficult to digest and may pass through the digestive system unchanged.
Suggestions
It is not recommended to feed popcorn to cats intentionally.
If your cat eats a small amount, it is unlikely to cause harm, but avoid giving them buttered or salted popcorn.
Monitor your cat for any signs of digestive problems or lethargy if they consume a large amount.
Note: even if labeled as safe, any food can potentially cause allergies. When introducing a new food, please feed a small amount and observe your cat for any allergic reactions.