Hi, MiiKey kindly optimize your device.
1. From the home screen, swipe either up or down to access apps.
2. Tap Settings.
3. Select battery and device care.
4. Tap Optimize now.
If the issue persists, please perform a soft reset of your device.
Press and hold the power and volume down buttons for about 10 seconds.
*The device may take a screenshot, however, keep holding the buttons for a few more seconds.