This isn’t new news as such, but people keep being surprised by it, so it’s worth repeating. Substack hosts, profits from, and promotes explicitly Nazi content, and if you are adding value to that network, you are helping them to do so. https://www.theguardian.com/media/2026/feb/07/revealed-how-substack-makes-money-from-hosting-nazi-newsletters
For people who want alternatives, Ghost is a Substack-style platform that doesn't host Nazis. Its software is free open source so you can self-host if you prefer, or use Ghost's own paid hosting service.
Ghost also has Fediverse compatibility so people can follow your Ghost blog or newsletter directly from Mastodon etc. More info at https://fedi.tips/ghost-blogs-and-newsletters-on-the-fediverse/
If you have a fediverse account, you can quote this note from your own instance. Search https://social.chinwag.org/users/FediThing/statuses/116030466826558660 on your instance and quote it. (Note that quoting is not supported in Mastodon.)