In maths the symbol i is used to denote the square-root of -1. It’s an imaginary number, an unreal but valuable concept. They’re useful, but most people go through life without being troubled by them or what they mean.
I often think all of the stats about the viva are kind of like imaginary numbers. It’s useful to know nearly everyone passes, that most vivas are finished in three hours or less, that around 85% of people get minor corrections. But to be well well-prepared for the viva you don’t have to dwell on the statistics.
They could be a confidence boost for you, but it’s far more valuable to regularly remember you lived the life and did the work that lead to your thesis. You’re a talented researcher: knowledgeable enough and experienced enough to meet the demands of the viva.
Don’t focus on the imaginary numbers: focus on what’s real.