I. Introduction
In today’s digital world, online service systems, such as search engines, e-commerce platforms, and social networks, have become an integral part of our daily lives. To ensure seamless service and maintain user satisfaction, IT operations engineers in these companies closely monitor Key Performance Indicators (KPIs) such as response time and success rate, providing a comprehensive overview of the system’s performance. KPI anomaly detection (KAD) plays a crucial role in identifying potential issues by detecting anomalies in KPIs, thereby accelerating the process of failure diagnosis and mitigation.