It’s very important for the Court to rule on this:

Today, the United States Supreme Court will hear three consolidated cases in Trump v. CASA on the growing use of national or universal injunctions. This is a matter submitted on the “shadow docket” and the underlying cases concern the controversy over “birthright citizenship.” However, the merits of those claims are not at issue. Instead, the Trump Administration has made a “modest request” for the Court to limit the scope of lower-court injunctions to their immediate districts and parties, challenging the right of such courts to bind an Administration across the nation.

That’s from Jonathan Turley, who also goes into the history of such injunctions:

Under President George W. Bush, there were only six such injunctions, which increased to 12 under Obama.

However, when Trump came to office, he faced 64 such orders in his first term.

When Biden and the Democrats returned to office, it fell back to 14.

That was not due to more modest measures.

Biden did precisely what Trump did in seeking to negate virtually all of his predecessors’ orders and then seek sweeping new legal reforms. He was repeatedly found to have violated the Constitution, but there was no torrent of preliminary injunctions at the start of his term.

Yet, when Trump returned to office, the number of national injunctions soared again in the first 100 days and surpassed the number for the entirety of Biden’s term.

Turley doesn’t explain why it was used so much more often against Trump, but my notion is that it’s because judges on the left are more inclined to employ it. Turley also doesn’t explain when national injunctions were first issued by lower courts, but I found some information on that here:

Commentators broadly agree that nationwide injunctions as currently understood did not exist in the pre-Founding English courts of equity, that no nationwide injunctions issued in the early years of the Republic, and that such injunctions have become more common in the last two decades.51 In a May 2019 address, Attorney General William Barr stated that federal courts “issued only 27 nationwide injunctions in all of the 20th century.” By contrast, as of February 2020, the Department of Justice (DOJ) had identified 12 nationwide injunctions issued during the presidency of George W. Bush, 19 issued during Barack Obama’s presidency and 55 such injunctions issued against the Trump Administration. Beyond the general agreement that nationwide injunctions have increased in recent years, scholars debate many significant points, including when the first nationwide injunction issued, whether other types of injunctive relief provide historical precedent for current nationwide injunctions, and the extent to which historical precedent is relevant to the legality of nationwide injunctions today.

There’s much much more at the link. Although left and right disagree on when it started and exactly how to define it, it seems to me that the practice really picked up steam against George W. Bush and has accelerated greatly against Trump. At this point, it’s the left’s main tool against him.

ADDENDUM:

See also this article which contains a discussion of some of today’s SCOTUS hearings on the subject.