Usually, no one can tell if you screenshot on a story. But some apps or platforms might have special technologies or rules to handle this, though it's not very common. So, you might be in the clear most of the time.
In most cases, no one would know if you screenshot a story unless the platform specifically has a notification feature for that.
Generally, it's unlikely that someone would be notified if you take a screenshot of a story. However, it depends on the settings and policies of the specific app or platform you're using. Some might have security measures in place to detect or prevent screenshots, but this isn't common.