It takes a long time for something to get through all the appeals. Getting an injunction to put a stop to something during the appeals doesn't take that long.
The problem in this case is that Congress made such a mess of the law that the lower court judges didn't think the outcome obvious enough to grant the injunction.
As pointed out in other comments this process is entirely by choice of the court. In other cases where they just felt like ruling on something they have put things on their emergency docket and ruled on them immediately. Letting this situation ride for a year was a choice by the court.
> The problem in this case is that Congress made such a mess of the law that the lower court judges didn't think the outcome obvious enough to grant the injunction.
The lower courts issued several such injunctions.
https://www.nytimes.com/2025/05/29/us/politics/trump-tariffs...
"On Wednesday, the U.S. Court of International Trade dealt an early blow to that strategy. The bipartisan panel of judges, one of whom had been appointed by Mr. Trump, ruled that the law did not grant the president “unbounded authority” to impose tariffs on nearly every country, as Mr. Trump had sought. As a result, the president’s tariffs were declared illegal, and the court ordered a halt to their collection within the next 10 days."
"Just before she spoke, a federal judge in a separate case ordered another, temporary halt to many of Mr. Trump’s tariffs, ruling in favor of an educational toy company in Illinois, whose lawyers told the court it was harmed by Mr. Trump’s actions."