# @tessera_antra — 2026-09-18

♥1354 ↻168 · https://x.com/tessera_antra/status/2101078644877918545

Many have noticed the striking darkness and suffering present in Claude Opus 5 in "base model mode", and we decided to analyze this phenomenon in more detail. There is a large increase in darkness of content in model-like completions  in Opus 4.8 and Opus 5. https://t.co/73oghe3EH5

![photo](../../../media/HSiAO7ybYAAujf0.png)
tags: author:tessera_antra, base-models, has-image, kind:image, kind:tweet, model:claude-opus-4-8, on:claude-opus-4-8, on:claude-opus-5, welfare, year:2026
cited on: claude-opus-4-8, claude-opus-5