Does the ruling on participating in AdSense differ if the profit varies from one country to another, based on the number of views or clicks, and this is considered an unknown percentage of profit?

There is no harm in the commission varying by country for viewing ads, as long as it is known. The permissibility of subscribing to the site is conditional on the subscriber's ability to have full control over the ads and block those that are forbidden; this is based on the Almighty's saying: "And do not cooperate in sin and aggression."