Anthropic's cache TTL was changed from 1 hour to 5 minutes around March 6th, causing a significant increase in cache creation costs and quota consumption for subscription users. The change was not announced and appears to have been made server-side. The author of the issue analyzed session data and found that the 1-hour TTL was the intended default, and the reversion to 5-minute TTL has caused a 20-32% increase in cache creation costs. The author requests that Anthropic confirm or deny the change and consider restoring the 1-hour TTL as the default.