OpenAI Codex Plus plan rate-limit costs spike 10-20x since June 16

According to GitHub issue reports, users on OpenAI's Codex Plus plan with gpt-5.5 model experienced a 10-20x increase in rate-limit cost per token starting June 16, 2026. The change reduced the typical 5-hour monthly budget from supporting 20+ prompts to 2-3 prompts, with no user-side changes to prompt size or frequency.