The (bullshit) scotus argument is that congress can’t grant decision powers to federal agencies cause hurrdurr constitution.
Basically, for ~40 years we’ve run on a SCOTUS decision referred to as the “Chevron Decision.” What that did is direct federal courts to defer to agencies on interpretations of relevant laws and statutes, because federal courts were being bogged down by every. little. bit. of. minutiae. around the practical application of a bills intention.“Agency says brown, interested party says black, BOOM LAWSUIT” is an exaggeration but not by much. Instead, Chevron gives agencies the room for experts in the field to draft appropriate regulations etc in service of congress’ bills. “Agency says brown, interested party says black, well too bad the experts say brown is the best choice.” Can’t tie them up in court over everything.
Now, with Chevron overturned, Republicans can start tying everything they dont like up in court again. Plus, with the hyper conservative activist SCOTUS judges, now they can run any regulation or policy straight up the appeal ladder to have them all ruled “unconstitutional” with only the occasional less important burner case turned down in a halfass attempt to look “impartial”