I know Kinder chocolate has never been popular in the US, but apparently Kinder did sell their chocolate surprise eggs for a while. The US deemed them a safety hazard since a child could choke on the toy inside or break their teeth.
Fast forward a few months to the US-Canada border. A woman was selected for search and US CBP found the contraband and fined her $300.
Stupid stuff like this is why I don’t bother bringing anything back from Canada when I’m there for business. If I’m flying then I will buy stuff after US Preclearance, but when I drive I don’t purchase anything to bring back. It makes it easier that way.