The wheel/hub is making a noise.

Edited

The clicking or buzzing sound you hear when coasting on your bicycle is completely normal and comes from the pawls in your rear hub (this occurs on all Prevelo bikes with pedals). When you stop pedaling, these spring-loaded pawls click up and down over the teeth of the drive ring inside the hub, producing the distinctive buzz you hear. This mechanism is essential for your bike's function, allowing you to coast without the pedals turning.

Premium hubs often have more pawls and engagement points, which can result in a louder, more pronounced sound. For detailed information about hub technology and why higher-quality hubs tend to make more noise, please visit our blog at: https://prevelo.com/blogs/news/the-science-behind-bicycle-hub-sounds-why-premium-hubs-click-louder