Is the SpaceX Merlin engine reliable?

Could you elaborate on the reliability of the SpaceX Merlin engine? With the increasing frequency of launches and the importance of mission success, it's crucial to understand the engine's durability and performance under various conditions. Are there any known issues or limitations that have been identified during its use? How does SpaceX ensure the reliability of the Merlin engine through testing, maintenance, and upgrades? Additionally, how does its reliability compare to other engines in the industry?