During January 2026, Muhun Kim contributed to the AdguardTeam/AdguardFilters repository by delivering a targeted bug fix that improved the accuracy of the subscriptions categorization filter. By analyzing user feedback and revenue management requirements, Muhun identified misclassification issues affecting hon.jp and addressed them through precise filter management. Working in plaintext, Muhun enhanced user experience by reducing incorrect classifications that impacted Google Revenue Manager integration. The solution involved end-to-end debugging and a traceable, single-commit patch, demonstrating attention to patch integrity and user trust. This work reflected a focused approach to filter management and user experience improvement within a collaborative open-source environment.