Opus 5.5 almost entirely stopped using em dashes, users observe
Outside-Iron-8242 · reddit · 2026-09-26
Reddit users, citing an ArenaAI comparison, note that Anthropic's new Opus 5.5 has almost entirely cut em dashes from its output — a notable behavior change, since the em dash has long been considered a hallmark tell of AI-generated text.
Related event: Text Arena: Opus 5.5 Writes More Like Humans, Em Dash Use Down 95%(5 posts)→
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