There is no rewards app anymore only the main site
Go to Google customer service, not the Google page for Hot Head Burritos.
This is a bad place to ask that question, but perhaps see if it works on data, if you are using wifi or vice virsa. If the app was recently updated, then maybe you'll have to wait for the next update to fix this error. If that's the case, you're probably not the only one experiencing it and they're working to fix it now. You could also try reinstalling the app.
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