Yes. Like others here, I did not know there was a paid Insiders tier. Just nudging free users with a “consider becoming an insider” hard sell splash screen upon each login with a 10 second countdown would go a long way towards encouraging users to join Insiders and might be enough to avoid going the ad route. Then you are still offering a free option but I think lots will sign up.

Redesign the donate/payment page for clarity. Enable Apple Pay to reduce friction.