Why does an app show a badge with an exclamation mark?

The exclamation/attention mark warns that an integrated account is signed out. You can either resolve this by signing-in, or hide the badge.

Restart Wavebox and click on the app icon. You should get a 'this is signed-out' warning. Sign in again, and the warning badge will disappear.

Search settings for 'Show app attention badge when logged out' and toggle this OFF.