Snapchat does notify people when you take a screenshot of others’ content on the app. The app will send an alert if you screenshot a photo or video, insert the message “You took a screenshot!” into the text if you screenshot a chat, and show a screenshot icon in the viewers section of a user’s story.
If you are looking for how do u know someone screenshot on snapchat then you must check out the given reference guide below to know more.
Access the Control Panel by swiping down from the top of the screen.
Locate and select the Screen recorder function.