They're entirely manual. A whole bunch of volunteers write filter rules to block known ads. There's a big github where people can post issues about ads they've

They're entirely manual. A whole bunch of volunteers write filter rules to block known ads. There's a big github where people can post issues about ads they've found, and volunteers will write filter rules to block them. See https://github.com/easylist/easylist/issues https://github.com/easylist/easylist/issues