"App with id: ###### not found" message is scary

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I'm always frustrated when I switch environments to check on another Amplify app and the banner is all red, scary, and obtrusive!


Additionally, the difference between "connect app" and "new app" is unclear. Why can I at times create a new app and other times only connect? (I know it's because certain envs aren't supported yet, but maybe make this more clear)


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We should communicate more clearly that
- When switching envs: nothing bad happened to your app, it's simply not in that particular environment - maybe make the banner more of an informational / more easily dismissible?
- "Maybe “Your app isn’t available in X region. We see it in Y and Z regions."
- Clarify on connects vs. new


**Additional context**
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All images by @njreid

The issue points to the environment-switching banner and the Connect/New app UI, illustrated by screenshots. Start by locating those UI entry points and review how unsupported environments are presented; done means the message is informational and dismissible, and the two actions explain when each is available.

Written by the indexing model from the issue text.