Spun content is freely usable everywhere.But using spun content for search engine optimization (SEO) purposes, such as for private blog networks (PBNs), is generally considered a black hat tactic and can lead to penalties or even complete de-indexing from search engines. Search engines like Google aim to provide users with the best and most relevant content, and using spun content goes against that goal.
As for whether spun content can be used on sites like Medium and Blogger, it is generally not a good idea to use spun content on any website, as it can harm the website's reputation and search engine ranking. Such platforms typically have strict guidelines for content quality and can penalize or remove content that violates those guidelines.
In summary i can tell you , spun content is not recommended for any website, whether it is a PBN, Medium, or Blogger. It is better to focus on creating high-quality, original content that provides value to readers and adheres to best practices for SEO.