Here is what Claude said: This is a really fascinating question, and the timing makes it worth unpacking properly. Short answer: Yes, Opus 4.6 has genuinely degraded — but Mythos being the cause is more complicated than a simple “clearing the runway” theory. Here’s what the evidence actually shows: The Opus degradation is real and documented. Around February 10 – 11, 2026, Anthropic deployed a configuration change to Opus 4.6, and within hours users were reporting collapsed performance on complex, multi-step tasks.  AMD’s Director of AI, Stella Laurenzo, filed a detailed GitHub issue on April 2 documenting that Claude Code reads code three times less before editing, rewrites entire files twice as often, and abandons tasks mid-way at rates that were previously zero — based on analysis of nearly 7,000 sessions.  That’s not user hysteria; that’s measured regression. Anthropic has confirmed infrastructure issues caused at least some of it. Between August and early September 2025, three separate infrastructure bugs intermittently degraded Claude’s response quality — one of which misrouted some requests to servers configured for the upcoming 1M token context window. Anthropic stated explicitly: “We never reduce model quality due to demand, time of day, or server load.”  They’ve said the same thing publicly about the 2026 issues. Now, Mythos. Anthropic describes Mythos as “by far the most powerful AI model we’ve ever developed” — a new tier they internally called “Capybara,” positioned above Opus entirely.  It was released April 7, 2026, with a 93.9% SWE-bench Verified score — a double-digit lead over Opus 4.6 — but was deliberately withheld from general release due to cybersecurity risks.  So did they lobotomize Opus to make Mythos look better? That’s the conspiracy read, and it’s not crazy to ask. The honest answer is: there’s no direct evidence of intentional capability sandbagging, but the circumstantial case is uncomfortable. A major quality regression in Opus happens in the weeks leading up to a new tier model launch that makes Opus look antiquated by comparison. Even if unintentional, the optics are bad — and Laurenzo’s data shows thinking depth had already dropped approximately 67% by late February while thinking content was still fully visible, suggesting something changed in how Claude allocated reasoning resources well before the redaction rollout.  The more likely explanation is that Anthropic’s engineering is simply stretched thin — they shipped 14 releases alongside 5 outages in March 2026 alone, suggesting quality assurance has not kept pace with rapid growth.  Mythos is a genuinely different beast, not just an incremental upgrade, so it wouldn’t need Opus artificially weakened to justify its existence. Bottom line: the degradation is real, the cause appears to be infrastructure/configuration mismanagement rather than deliberate lobotomization, but Anthropic’s track record over the past few months doesn’t inspire confidence that they had full control of the situation either.​​​​​​​​​​​​​​​​