As I read it, the US Supreme Court basically told the Trump admin they can finish forming the rule they want to use with the USPS to put restrictions on mail-in ballots, then states can sue for harm, whereas at the point the states were suing and the injunction given the final rule wasn't ready yet. The USPS finished that Aug 21, 3 days ago, and will officially publish it Aug 26, two days from writing.
However the same judge in Boston separately prevented any new rule coming into effect for the Nov 2026 elections, so that needs to be overturned. Additionally, after Aug 26, the states can sue again probably and obtain an injunction on the published final rule, to keep the plan being implemented even if the "no new rules before November" injunction is defeated.
(My editorialization) So the Supremely Corrupt Six are wasting federal and states' and the court system's money and time just to go out of their way to give the Trump admin small favours.