The problem of #Substack is old: "Launched in 2017, the platform has previously faced criticism for hosting newsletters that promote #extremist views. Its co-founder, Hamish McKenzie addressed its decision to host #Nazi content in one of his own posts on the site in 2023."
But now #algorithms even promote it! "Substack #algorithm directed the Guardian’s account to 21 other profiles featuring similar content." https://www.theguardian.com/media/2026/feb/07/revealed-how-substack-makes-money-from-hosting-nazi-newsletters