Does Signal Screenshot Notify the Other People or Not?

Yes, Signal does notify the other person when you take a screenshot of a disappearing message or an image sent in disappearing messages mode. Signal will show a small notification at the bottom of the screen letting the sender know that a screenshot has been taken.

Under What Circumstances Does Signal not Send Notifications? 

For regular messages (non-disappearing), Signal does not notify the other person if you take a screenshot. This means that, while it does have privacy protections like disappearing messages, it doesn’t track or notify screenshots for regular, non-temporary messages.

So, the main scenario where a notification would pop up is when you're viewing content in disappearing message mode and taking a screenshot.

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