Takes a little bit of work to set up.

Blocking whole sites/domains takes the right formatting.

If you want to black all of pinterest or every fandom "wiki" you need to format your block rule like this:

*://*.fandom.com/* or *://pinterest.com/*

If you just put *.fandom.com/* it won't block anything at all.

And with sites like pinterest that have different country versions you may have to block multiple domains i.e. *://*.pinterest.com.au/* *://*.pinterest.com.nz/* etc.