Hi @Jason_F, This warning indicates that, the app is using one of the standard “app logos” that the AppSheet editor provides.
To get rid of this warning,you may wish to add your own app logo by going to option UX - > Brand - > App Logo
Also please note that as per my understanding, this is only a warning and you may still deploy your app,
using one of standard app logos that the AppSheet editor provides.
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