Google AI Mode and Your Activity
Google AI Mode can be accessed at google.com/ai. A disclaimer may appear under the search box stating "Based on your Google activity," but this only seems to show when signed into a Google account.
This makes sense, as Google requires access to a user's account to know their past activity history. Google AI Mode does utilize search and conversation history, likely to continue chats from where they were left off.
Based on your Google activity
A note on the AI Mode page mentions default suggestions are also "Based on your Google activity."
Note: The author is currently offline for Simchas Torah.
Author's summary: Google AI Mode uses user activity for suggestions.