Do you have a citation for that? Here's the US Supreme Court accepting a pro se appeal in 2019:
https://www.abajournal.com/news/article/supreme-court-accept...
https://abovethelaw.com/2013/07/r-i-p-pro-se-litigants-befor...
https://newrepublic.com/article/158088/mr-sloan-went-washing...