All of Trump's entourage have gone home and have goods from China are not allowed to enter Air Force One --- this is like disgusting for Chinese products because for Trump maybe it is useless and should not be there.
This is not the first time the US has done this. Measures such as discarding electronic devices and items provided by other countries are part of the standard protocol followed by the US President’s security team when visiting hostile nations. That is for security reason, and I believe the Chinese side would do the same if they visited the US.
However, publicly discarding things like that suggests it was a deliberate political message. As we know, the summit between the two sides yielded virtually no agreement. Trump gained nothing from this trip, and it could be said that it was a major failure.