Hi @KayBurks589, revenue share is determined by many factors. I recommend you contact firstname.lastname@example.org and the team will gladly provide additional details to your specific situation.
Simply because your course is on sale for $10.99 most of the time via Udemy's flash sales. (Especially in November when you posted this)
So, you'll get ~ $5.00 (50% split) when someone enrolls via discovery or browsing Udemy, and around ~ $2.50 (25% split) when an enrollment came from Udemy advertising your course via Facebook ads etc... They pay to get the ads out there, and serve you their built in audience - so that is the price we pay. I believe it is fair.
Hope that helped!
Oh and if you want to take marketing into your own hands, go to "promotions" inside your curriculum tab and use the instructor link for your course to promote if off-site. This will ensure any enrollments coming from your instructor link give you (almost) the full price 97% of revenue.