Trump is claiming Americans have not seen the full benefit of tariffs yet, because importers filled their storage facilities prior to the tariffs.
This is simply not true. While the tariffs were introduced quickly, importing shipping containers from China can easily take 40 days.
Importers have stopped importing, because no one dares to buy the heavily tariffed goods, when a competitor may buy at a lower price next week, when Trump changes the tariffs again.
I don't know why you would be surprised.
Even Trump's own supporters occasionally admit that he says false things all the time, so why would he stop saying false things in this topic?