Tariffs are not treaties, they're taxes/duties - only Congress has the power to raise them. Article I is extremely clear on that. Historically, tariffs were always raised by acts of Congress, not by Presidential fiat.

Trump is using extremely misguided legislation from the 1960s/70s where Congress allowed the President to enact tariffs for national security and emergencies. There is a very strong argument (in the sense it resonates with the conservative SCOTUS majority) that Congress cannot delegate its fundamental powers to the executive by legislation alone.

I think people are just too cowardly to bring a case in front of the courts to challenge the constitutionality of it all. Non-delegation doctrine is what the Federal Society want to use to kneecap all federal regulation. Trump operates on a spoils system so it's not in the interest of conservatives or businesses to challenge him, for fear of retribution.