When we say UX affects revenue, people usually assume we mean it looks better. We do not. We mean reducing the number of decisions a person has to make to reach their goal.
Every extra form field, unclear choice and unnecessary page loses some users. Those losses multiply instead of simply adding up.
A concrete Persian example: a form that renders a phone number with incorrect bidi isolation leaves the user unsure whether the number went in correctly. That small hesitation matters at scale.
Another: speed. A page that takes three seconds longer on a mobile network loses a share of visitors before they see anything at all. That is a design problem as much as an engineering one, because the decisions about image weight and font count are made during design.
A practical method: write out the main revenue path, count the steps, and for each one ask "what breaks if we remove this?" The answer is usually "nothing" more often than you would expect.