Identify the Issue and Clarify the Metric:

Confirm that the 25% drop is accurate and not due to a data reporting issue. Make sure the decrease is specifically for monthly active users in India, and not globally or regionally.

Analyze the Pattern:

Is the drop sudden or gradual? If it's sudden, it might point to a significant technical issue, a significant change in market conditions, or a new product/feature release. If it's gradual, it could be related to increasing competition, declining product performance, or changes in user behavior.

Internal Factors:

1. Product Changes: Review recent updates, feature additions, or UI changes that could've affected user experience.
2. Technical Issues: Explore potential technical problems, such as app crashes, login problems, payment issues, etc. Segment the user base by device type, OS, and app version to detect specific patterns.
3. Marketing Efforts: Examine recent marketing campaigns, promotional offers, and changes in user acquisition strategies.

External Factors:

1. Competition: Investigate if a new player has entered the market or if existing competitors have made significant changes.
2. Regulatory Environment: Check if there have been any regulatory changes that might have affected our services.
3. Macroeconomic Trends: Consider broader economic conditions. Has there been a significant event, like a recession or pandemic, which could affect consumer behavior?

Look at Related Metrics:

Check related metrics like daily active users (DAUs), user engagement, transaction volumes, customer satisfaction, and churn rate to get a broader picture.

User Feedback:

Review user feedback, complaints, and reviews to identify any common issues or areas of dissatisfaction.

Develop Hypotheses and Test:

Based on the gathered information, form hypotheses on why MAUs might have dropped. Test these hypotheses using further data analysis, user surveys, or A/B tests.

Act on Findings:

Once the root cause(s) is identified, plan a course of action. This could range from technical fixes, product changes, and new marketing strategies, to a shift in business direction.

Communicate:

Keep all relevant stakeholders informed throughout this process. This includes not only your internal team but also the broader organization.

Review and Monitor:

Once changes have been implemented, monitor the metrics closely to see if the situation improves. This is a continuous process of learning and iteration.