There’s a common worry among PhD candidates that examiners see all and know all. They have understood your thesis perfectly even before they’ve finished reading it. They can find the problems that you didn’t even notice. Their opinion is what counts.
A favourite analogy that helps me tell others about viva prep is to think of their thesis as a star, and think of their examiners’ work like constellations. Your examiners know more not because they are innately better than you, but only because they have had longer to do their work than you.
Keep things in perspective. They have experience; you have expertise.