Hard to tell. It sure seemed like a majority opinion.
Which five or six justices signed on to it?
It would say something along the lines of: “Justice Alito, joined by the Chief Justice, Justice Thomas, Justice Gorsuch, Justice Kavanaugh, and Justice Barrett.” (if it were a 6-3 decision).
If no such indication, this is not an official opinion and is merely Justice Alito’s opinion he has drafted and seeing if can get a majority of justices to agree and join him.
When you read, did you confirm it was a majority opinion?
Hard to tell. It sure seemed like a majority opinion.
It starts with “Opinion of the Court.” So yes it is a draft majority opinion. Since Alito drafted it it PROBABLY means Roberts isn’t on board. He COULD be in a concurring opinion - which is concurring in the result, not the reasoning. So it could be 5-4 or 5-1-3.