The behaviour that you describe is most likely attributable to a stuck/hung background process. However, there is insufficient information to make a definitive diagnosis as to cause.
Perform a forced-restart of your iPad - as this will often clear an isolated software issue:
Force restart iPad (models with Face ID or with Touch ID in the top button)
If your iPad doesn’t have the Home button, do the following:
- Press and quickly release the volume button nearest to the top button.
- Press and quickly release the volume button farthest from the top button.
- Press and hold the top button.
- When the Apple logo appears, release the top button.
Force restart iPad (models with the Home button)
Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
After the restart, fully charge your iPad - and then monitor performance over the coming days.
Speaking of personal experience - assuming that your iPad battery is otherwise healthy - the issue is perhaps unlikely to recur. I have myself seen a similar event only one or twice in the last ten years (across multiple devices).
