Referring-domain totals come from the public Common Crawl graph (full page/anchor index like Ahrefs is paid-only). Linking pages and anchor texts below are a live web sample.
mc.g/404;rs40_shard.sel:4/not found;rs39_22.sel:3/not found;rdb.g/no such key;DBD/404;v4.get:14/Document not found;rwro.get:22/Document not found;RS.dbs:22/Document not found;RS:22/404;mc.g;DC;IO:25