Tamika Johnson, a 44-year-old in Chicago, posted videos to TikTok this month about her orders from Shein, the Chinese e-commerce giant. She was nervous about potential delivery delays in the face of upcoming tariffs.

Her 213,000 followers chimed in as she shared status updates on her purchases of clothing and suitcases, detailing their own plans for last-minute orders and sharing concerns about their shipments.

“People are very worried,” Ms. Johnson, who posts to TikTok under the handle @TammyTheBlackPrepper, said in an interview. “I’m trying to stock up on clothes now and the things that I need.”

Ms. Johnson is one of many American consumers who have been posting anxiously to TikTok and Reddit about a coming Trump administration-induced change for the Chinese e-commerce companies Shein and Temu, which sell inexpensive items like $8 dresses and $14 wagons. Starting on May 2, the Trump administration is poised to end a trade loophole that enabled the delivery of ultra low-cost goods from Chinese factories straight to Americans’ doorsteps without being subject to duties. That will add steep new fees to packages from Shein and Temu.

At least some sellers on TikTok Shop, the popular app’s growing marketplace, and AliExpress, another Chinese e-commerce site, will also take a hit.