But Bard will also analyze the private content of messages “to understand the context of your conversations, your tone, and your interests.” It will analyze the sentiment of your messages, “to tailor its responses to your mood and vibe.” And it will “analyze your message history with different contacts to understand your relationship dynamics… to personalize responses based on who you’re talking to.”
Appointments with doctors is too sensitive of data. I would opt out of that & just add it to your non-Google calendar as soon as you know the date+time.