Revenue would have gone up, because you now have to buy a ticket for 3 parks, not two, that would be up to 50% increase in ticket revenue. Many different businesses put their prices up immediately after the pandemic even though actual visitors dropped and it looked like they weren't any worse off.
The thing they feared- Epic cannibalising IOA/USF appears to have happened, but the plan was originally to have a few new things open in north campus to balance out the new park then epic got more expensive. They're only just getting round to building those now.
This should act as a cautionary tale for the dumbass idea to put Orlando attractions in Universal Studios London. Why rob Peter to pay Paul?