Hey there Worried_user1023,
We appreciate those additional details. From here, we first recommend trying to restart your iPhone 8. Restarting can refresh the iOS and sometimes help resolve unexpected issues. If needed, the steps below show how:
"How to restart your iPhone 6, 7, 8, or SE (2nd or 3rd generation)
- Press and hold the side button until the power-off slider appears.
- Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
- To turn your device back on, press and hold the side button until you see the Apple logo."
Those steps are from this article: Restart your iPhone - Apple Support If a restart doesn't help, you'll also want to ensure that your iPhone 8 is fully up-to-date, as updating can sometimes help if the current iOS is having any issues. The steps below will walk you through that:
"Update your iPhone or iPad wirelessly
- Back up your device using iCloud or your computer.
- Plug your device into power and connect to the internet with Wi-Fi.
- Go to Settings > General, then tap Software Update.
- If you see more than one software update option available, choose the one that you want to install.
- Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do."
Those steps, and more information, can be found here: Update your iPhone or iPad - Apple Support
Please let us know if those steps help stop the screenshot animation from happening or if you've already tried those steps.
Take care.