This is a known issue that we are currently monitoring but based on user feedback, it doesn't seem to be isolated to the Notability app. Based on our investigation, we believe the problem is specific to users using Apple Pencils on the iPad.
Reach out to Apple with recorded evidence of the behavior to replace the device. In the meantime, the following ideas may assist in lessening the occurrence:
1. From within a Notability note, disconnect the writing device via the Note Options (3 dots) > Info > Disconnect.
2. In your iPad's Settings, disconnect the writing device via Bluetooth. Reconnect both.
3. In your iPad's Settings, go to "Apple Pencil" and disable "Only Draw with Apple Pencil".
4. In your iPad's Settings, go to "General > Accessibility". If "Zoom" is enabled, try turning it off.
5. In Notability's Settings, go to "Handwriting" and toggle "Tap and hold" off and back on.
6. In Notability's Settings, go to "Handwriting" and turn "Palm detection" off.
7. If you can, don't use Notability while charging the device.