Anthropic is facing a wave of user backlash over reports of performance issues with its Claude AI chatbot

Anthropic, the high-flying AI company, is facing a backlash from some of its most prolific users over a perceived decline in the performance of its Claude AI models.

The issues have left the company—recently valued at $380 billion and reportedly en route to an IPO—scrambling to respond to user revolt and online speculation about its motives and its ability to serve its newest wave of customers.

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Anthropic’s popular Claude AI model has seen a significant decline in performance recently, according to many developers and heavy users, who say the model increasingly fails to follow instructions, opts for sometimes inappropriate shortcuts, and makes more mistakes on complex workflows.

The complaints appear to be connected to recent changes Anthropic quietly made to the way Claude operates, reducing the model’s default “effort” level in order to economize on the number of tokens, or units of data, the model processes in response to each request. (An Anthropic spokesperson has said publicly that the change was listed in the changelog, a running list of updates available to users.)

The more tokens processed per task, the more computing power that task consumes. And there is widespread speculation that Anthropic, which has announced fewer multibillion-dollar deals for data center capacity than some of its rivals, may be running short of computing resources after adoption of its products soared in the past few months.

User dissatisfaction with Claude’s sudden performance decline and anger at Anthropic’s perceived lack of transparency could potentially derail the company’s runaway growth, just as it is hoping to woo investors for a potential IPO. The claims that Anthropic has not been candid about the changes it has made to the way Claude operates or the way the changes may increase the cost for using Claude are particularly threatening to Anthropic because it, more than any other AI company, has tried to build a brand reputation on being more transparent than other AI companies and more aligned with its users’ interests.

Anthropic declined to answer Fortune’s specific questions about Claude users’ complaint on the record. Boris Cherny, the Anthropic executive who leads its Claude Code product, responded to user complaints online by saying that Anthropic had reduced the default “effort” Claude makes in answering user prompts to “medium” in response to user feedback that Claude was previously consuming too many tokens per task. But many users complained that the company had not highlighted this change to users.

The situation has caused a pile-on of speculation and allegations—including from some of its competitors—that the company is purposely degrading performance owing to a lack of compute capacity.

Across the industry, AI companies are facing rising GPU costs, constrained data center expansion, and difficult tradeoffs over which products to prioritize as demand for “agentic” AI systems accelerates faster than infrastructure can scale. While an Anthropic spokesperson has said publicly that the AI lab does not degrade its models to better serve demand, there are reasons to believe the company is facing more acute constraints than some rivals.

Anthropic suffered a series of recent outages as usage has increased and has introduced stricter usage limits during peak hours, drawing complaints from some users. In an internal memo reported by CNBC, OpenAI’s revenue chief also claimed that Anthropic had made a “strategic misstep” by not securing enough compute capacity, and was “operating on a meaningfully smaller curve” than competitors. (Anthropic declined to answer CNBC‘s questions about these claims.)

Meanwhile, Anthropic also announced last week that it had trained a new, yet-to-be-released model called Mythos that is significantly more capable than its Opus AI model—but which is also larger and more expensive to run, meaning that it likely consumes more computing capacity than prior models. Anthropic stressed that it’s not releasing the model to the general public yet because of security concerns, but some have questioned whether Anthropic lacks sufficient compute capacity to support a broad Mythos rollout.

Victim of its own success

The scrutiny of Anthropic underscores the fast-changing nature of the AI market and the stakes involved. Just last week, Anthropic stunned the industry by announcing that its annualized recurring revenue, or ARR, is now $30 billion, up from $9 billion at the end of 2025. OpenAI said last month that it is generating $2 billion a month in revenue, or $24 billion a year, although the two companies do not report revenues in exactly the same way, making direct comparisons problematic.

Anthropic has recently benefited from a flood of new users, first owing to the popularity of its AI coding tool, Claude Code, and later from a wave of consumer support that followed its feud with the U.S. Department of Defense. Many users switched to Claude from rivals such as OpenAI’s