It depends on your account and seems to be random.

On my personal Max 5x account it’s not default and if I force it, it says I’ll pay API rates past 200k. On my other account that I use for work (not an enterprise account just another regular Max 5x account) the 1M model has been the default since that rollout. I’ve tried updating and reinstalling etc, and I can’t ever get the 1M default model on my personal account.

Based on other comments and discussion online as well as Claude code repo issues, it seems I’m not the only one not getting the 1M model for whatever reason and the issue continues to be unresolved.