At the Volokh Conspiracy, Ilya Somin has a piece that provides a policy critique of this decision from his Cato colleague David Bier and then a discussion of the legal issues. Here’s some of the legal discussion:

As David Bier notes, the new $100,000 fee is likely illegal, because the statutes authorizing H-1B fees only allow for fees to recoup administrative costs and some other types expenses. They certainly don’t authorize anything remotely resembling a $100,000 fee.

Trump is trying to get around these constraints by relying on  8 U.S.C. Section 1182(f), gives the president the authority to “bar the entry of any aliens or of any class of aliens into the United States” whose admission he finds “would be detrimental to the interests of the United States.” …

[I]t is far from clear that Section 1182(f) and Trump v. Hawaii give the president a blank check to exclude any potential immigrants for any reasons he wants, or to impose any fees he wants. In 2020, as David Bier also notes, Trump tried to impose a similar ban on new H-1B visas, but a federal district court ruled against the ban. As the court pointed out, ” there must be some measure of constraint on Presidential authority in the domestic sphere in order not to render the executive an entirely monarchical power in the immigration context, an area within clear legislative prerogative.”

The Supreme Court has repeatedly indicated that immigration is an area of legislative power. If so, there must be at least some constraint on how far it can be delegated to the executive.