It was a known promo duration. Everyone knew when the free time was going to be over.
The majority of your token costs are spent in codex ‘thinking’ or ‘reasoning’.
Reasoning is still the same price it’s always been with the regular ChatGPT.
Do your reasoning and planning in ChatGPT, and have it give you the prompts to make what you want to happen in Codex after your extensive exploration or short descriptions of what you need to happen in code.
They didn’t pull the rug out from anyone, it’s been known from day one of the prompt when the rates would expire at the end of the promotional period.