No one left ChatGPT over that deal: they decided to try Anthropic's Claude because the Department of War gave them free marketing.
My experience has, for a few months, been that OpenAI's models are consistently quite noticeably better for me, and so my Codex CLI usage had been probably 5x as much as my Claude Code usage. So it's a major bummer to have cancelled, but I don't have it in me to keep giving them money.
I'd love to get off Anthropic too, despite the admirable stance they took, the whole deal made me extra uncomfortable that they were ever a defense contractor (war contractor?) to begin with.