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To give an example how this can work. This is the system that exists in Germany. We have here 5 different branches of courts, the "general court" for civil and criminal matters, the labour courts, the governmental courts for all general lawsuits against the government, the financial court for everything taxes, and the social courts for everything social security.
Each of these courts have their own court buildings, their own districts, their own judges, and exist independent next to each other.
Edit: Also, these kind of injunctions, because they come from a state instead of a private citizen, would probably not be handled at these levels, but there would be a call to the constitutional court (our version of supreme court) right away, because it would involve a conflict of state vs. federal rights.
It’s a problem.  Anyone who wants to block a new policy can bring any number of suits to any number of judges — you only have to find one judge who agrees with you.  There’s no sport in the world in which 1-30 constitutes a winning season. >

Would an example of this be the student loan forgiveness Biden signed which was ultimately blocked by a single federal judge? >

Yes, absolutely. >

Not sure how it could be implemented, but maybe you just shouldn't be able to choose where to file a complaint if it's not solely affecting that jurisdiction? Like, if the complaint is concerning a national matter, it should be arbitrarily assigned to a random federal court. >

There's actually things like the US Federal Circuit, which is a specialized circuit that only hears appeals on certain cases regarding the federal government.  It could probably make sense to create an analogous jurisdiction of trial courts that are not "districts", but rather designated courts of first hearing on such matters.
That or you just let whatever district courts have first hearing but remove appellate jurisdiction away from the regional circuits.