It just happens from time to time. No idea of what causes it. Sometimes happens several times in a few minutes. Other times it may happen only once in a few hours.
[Re-Titled by Moderator]
Apple Watch Series 7, watchOS 11
Has the battery ever been replaced by Apple? Depending on the age and use, the battery might be defective and expanding, pressing against the screen and causing this white circle.
This may be a weather complication. We don’t have nearly enough information to judge the context of this cloud’s appearance.
Check the weather on Apple Watch - Apple Support
Why does my Apple Watch show an oval white cloud over for a few seconds?
