Nothing is censorship-free, but the social web (the fediverse) is just a bunch of websites. A website can be blocked at the DNS level, but that is exceedingly rare. Other websites may choose to block your site for their community. That is the way of the web.
Each site has different rules and cultures. It's convenient to sign up at someone elses site, but you give up some control. Want to live by your own rules? Put up your own website and participate in the social web that way!
I run my own GoToSocial website, which is a Go project that is much simpler to install and maintain than Mastodon. Hit the sweetspot for me, at least.