“understand from the Oct’s Cohort what has changed that they didnt like in the app” It might not be an app problem. Your early users maybe had different expectations or behaviours.
Retention rate drops to 30% by month 3 then remains stable until month 8.
The number of users/profiles has increased from 26 to 431. The retention behaviour will be difficult to compare e.g. Month 2 80.77% in Oct 2023, 32.25% in Jun 2024.
Consider the timeline of changes you made to the product/business to understand why retention has changed.
