How do I fix website log in issue on my MacBook Pro Safari?

When I attempt to log onto my Vanguard account using Safari and stored bookmarks I get a brief look at the Vanguard log on page then it goes to a brief summary of Vanguard not the official Vanguard page. I try saving new bookmarks but that doesnt work. A similar thing happens when I try to use Wikipedia, instead of the normal rich information I get a brief synopsis. It appears somehow that AI has taken over my requests. How do I revert back?

[Re-Titled by Moderator]