Your app has 200 users. 180 of them haven't opened it in 3 weeks.
That's not a retention problem. That's a 'why does this exist' problem.
Most founders hit their first 200 users through friends, warm intros, college networks. Then growth stops.
Because those 200 weren't your real customer. They were your audience.
Real customers come back because they need it, not because they know you.
If you lost your entire current user base tomorrow, would your product survive?
If the answer is 'I'm not sure' - the product isn't ready.
Talk to the 20 who came back on their own.
Ignore everyone else for now.