Periscope was originally released by Twitter as a standalone livestreaming app, before most of its functionality was baked into the main Twitter mobile app in 2016. Since then, Periscope's dedicated community has mostly shifted to Twitter and other platforms, and now the app that started it all is going away.
"The truth is that the Periscope app is in an unsustainable maintenance-mode state," Periscope said in a blog post, "and has been for a while. Over the past couple of years, we’ve seen declining usage and know that the cost to support the app will only continue to go up over time. Leaving it in its current state isn’t doing right by the current and former Periscope community or by Twitter. "
The current plan is to turn off new account creation "with the next release," then remove Periscope from the Google Play Store and Apple App Store on March 31st, 2021. You'll be able to download archives of streams until March. Periscope Studio, which allowed anyone to broadcast to Twitter/Periscope using desktop software like OBS, will be merged into Twitter Media Studio. However, Media Studio is currently invite-only.