Apple originally claimed that the Samsung Galaxy phones were a direct counterfiet of their work. They sued, and Samsung made changes.
OnePlus buds are a new product (I think released in 2020). It's probably just an honest mistake by the CBP, but it could also be they have some official direction to seize these OnePlus products either because Apple considers them to be infringing, or the Feds are acting as part of the broader trade-war.
It'd be like CBP seizing a bunch of Samsung Galaxy phones, claiming they saved the USA from counterfeit iphones.
I really hope I'm missing something.