OpenAI/ChatGPT/Codex, Anthropic/Claude and Google/Gemini all do this.
1. Everyone doing this doesn't mean it's acceptable.
2. Google Gemini explicitly says right under the chat box if you are a paid subscriber (Workspace):
Your <company name> chats aren’t used to improve our models. Gemini is AI and can make mistakes.
Not sure about the others.https://privacy.claude.com/en/articles/10023555-how-do-you-u...
This is incorrect. If you are a paid subscriber, Gemini explicitly states it doesn't use your data to train its models.