In todays World, near anything is possible, but this story has all the hallmarks of a Facebook story. Zero supporting evidence, zero involvement of a Avian Medical Professional, zero reporting back to any level of government oversight agencies.
Packaging is problematic to begin with as any number of toxic agents are used or come in contact with the box. Care should be taken.
FYI: Personally, I would be more concern with the vast amounts of Hand Sanitizer use, especially in small enclosed areas. That product displaces oxygen...
Yes Facebook, so could be any numbers of reasons, as not widespread? One case was definitely caused by the box as person had a Necropsy done after their Umbrella cockatoo past away shortly after tearing up the box and bird has no Prior health issues? One major online retailer, not going to name company is known to spray pallets due to COVID-19 protocols they have in place. Two other birds that past away are questionable as no tests were done to confirm.
More of a be cautious, then a widespread panic issue. Something honestly I didn’t even worry or think about myself. Still say avoid boxes for now due to more of a consequence of COVID-19 protocols in place, more then placing blame on retailers. Hence reason not going to mention company. It a much different time and anything is possible and not of the norm?