Claude Fable relaunch disappoints users with nerfed performance

Claude Fable, the company's most powerful model, is now available to all users, but early impressions are disappointing, as it appears to be nowhere near the original release.

When the Department of Commerce announced that it was lifting the ban on Claude Fable, I was holding my breath and counting seconds for the model to show up on Claude Code. I had also loaded up my usage-based credit wallet, just in case the model debuted as strictly usage-based.

To our surprise, Claude Fable shipped for everyone, including those with a $100 Max subscription, but there are multiple restrictions.

According to Anthropic, while Fable 5 is included in Max, Pro, and Team plans, it is heavily capped.

For example, you can use Fable for up to 50% of your weekly usage limits, which is not significant for such a powerful model. But it'll get worse after July 7, as the model will transition entirely to a pay-to-play system via usage credits.

However, the real gut punch is the degraded performance, or as famously used in the AI community, the "nerfed" performance.

On Reddit, users are reporting that the restored Fable 5 feels weaker, or is simply being routed through stricter safety systems more often than before.

"The new guardrails are kicking in on way too many tasks and falling back to Opus 4.8," one user wrote in a Reddit post. "This is not the model that got banned."

The problem is not just limited to Claude desktop, as Claude Code is also struggling with similar issues.

One user said Fable "didn't even let me search for dead code without switching to Opus," while another said it was "very very obvious" when the fallback triggers because Claude tells the user and visibly shifts to Opus.

Another developer claimed the model was unusable for some systems-level coding work, saying that C, C++, Rust, Win32 API references, memory-related work, and files mentioning words like "security," "vulnerable," "unsafe," or "hook" appeared to trigger a fallback or block.

Fable 5 may still be powerful when it actually handles the task, but the restored version appears to be far more sensitive to prompts, project files, and security-adjacent language.

However, BleepingComputer understands that the model itself has not been nerfed. Instead, it is likely that Anthropic is being extra careful with the safety guardrails, which is negatively affecting Fable's daily use cases.

In fact, we observed that Fable is sometimes routed to Opus 4.8 even when the task does not appear to be a safety risk.

Anthropic has said that its updated safeguards rely on a large "safety margin," which could explain the subpar experience some users are seeing with Fable.

Anthropic hasn't acknowledged the reports of false positives yet, but it's likely the company is aware of the problem and will address it in a future update.