There[SQ]s no known app called "Daff Moon Phase" on the Google Play Store. It[SQ]s possible :

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The name is slightly different:

Try searching for variations of the name, like "Daffodil Moon Phase," "Daff Moon," or similar terms.
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It[SQ]s a very new or obscure app:

Newly released apps might not have widespread visibility.
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It[SQ]s not available on the Play Store:

The app might only be available through other app stores or directly from the developer[SQ]s website.
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It[SQ]s a misspelling:

Double-check the spelling.

If you can remember any other details about the app (developer name, icon, description), that would help in finding it.