We would have preferred to ship an app with these alerts turned off by default, but Apple's App Review asked for them to be turned on.

You can turn them off individually in the app settings:

• Tap on the gear icon
• Scroll to AUDIO ALERTS
• Tap on any item's menu and select "Off"

Silence is golden :-)

If Storage was one of the things causing the alert, check out this knowledge base article about how storage space is computed and why it's different than what iOS/iPadOS reports.