Anthropic literally don't allow you to use the 1M context anymore on Sonnet and Opus 4.6 without it being billed as extra usage immediately.
I had 4.5 1M before that so they definitely made it worse.
OpenAI at least gives you the option of using your plan for it. Even if it uses it up more quickly.
Is that why it says rate limit all the time if you switch to a 1M model on Claude now? It kept giving me that so I switched to API account over the weekend for some vibe coding ran up a huuuuge API bill by mistake, whooops.