People repeating this is, I believe, an attempt to use the mere exposure effect (aka reiteration effect), to just get people used to hearing this and that it could happen. Advertising works. And lots of times familiar things can seem ok just because they’re familiar, even if they’re bad. It’s not that bad things won’t happen. We’re definitely working under an authoritarian regime. But the issue is that a lot of it is hype and also misunderstandings of both the law and the logistics and the problem with helping them spread this propaganda.
Here is a lawyer youtuber explaining the logistics and legal issues in a video to share with people who mention being worried about the insurrection act or martial law, but who won’t be willing to read articles and whatnot.
Also, April 20th is the day that Trump asked for a determination on how he can use it, not the day that he claimed to want to use it. But I think it should be a scandal that he picked the birthday of the reviled Nazi.