Just something MAGA-people seem to have a hard time with sometimes. Probably not as much when Americans are speaking to themselves, but as a non-American, sometimes it’s challenging to get “those people” to admit that there is indeed anything wrong with the US. As in they won’t accept a single criticism, and will loudly proclaim “America is the greatest country in the world”, while wearing a “Make America Great Again” hat, which for me pretty explicitly means America isn’t great, if it has to be made to be such again.
I think they’re probably referring to tax brackets and how much the ultra wealthy were taxed back in the 50s or something