Not sure exactly, but international trade law is weird, and generally bills of attainder are targeted at one or more individuals rather than classes of individuals. If a law defines a class, like "anyone selling goods from China" then I don't think it qualifies as a bill of attainder. I did find this article on Lawfare from 2019 where Huawei challenged parts of the NDAA because it specifically forbade the executive branch from buying Huawei gear. The courts ultimately did not agree with Huawei.